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Step-by-step solution for: SOLUTION: Points Lines and Planes Worksheet - Studypool
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Step-by-step solution for: SOLUTION: Points Lines and Planes Worksheet - Studypool
Let's go through each question in the worksheet and verify or correct the answers based on geometric principles. The images show three separate geometry problems involving points, lines, and planes.
---
Diagram: A parallelogram $ABCD$ with diagonals $AC$ and $BD$ intersecting at point $W$. Points labeled: $X$, $Y$, $Z$, $F$, $V$, $T$, $P$, $R$, etc., along the sides and diagonals.
#### a) How many points appear in the figure?
- Count all labeled points: $A, B, C, D, W, X, Y, Z, F, V, T, P, R$
- But from diagram: $D, X, Y, Z, A, F, V, T, P, R, W$ — total of 11 points.
- ✔ Answer should be 11, not 10.
> ✘ Incorrect: "10" → Should be 11
---
#### b) How many lines appear in the figure?
- Lines shown:
- $AB$, $BC$, $CD$, $DA$ (sides)
- Diagonals: $AC$, $BD$
- So far: 6 lines
- But there are also segments like $XF$, $YZ$, etc., but those are parts of lines.
- However, in geometry, lines are infinite; line segments are finite.
- In this context, they’re likely asking for line segments or distinct lines drawn.
- But since it says “lines,” and only two diagonals and four sides are drawn as full lines, that’s 6 lines.
- But looking closely, the diagonals are drawn as lines through the center, so we have:
- Line $AC$ (passes through $X$, $W$, $Z$)
- Line $BD$ (passes through $Y$, $W$, $F$)
- Sides: $AB$, $BC$, $CD$, $DA$
- So 6 distinct lines.
- But answer is given as 2 → That’s incorrect.
> ✘ Incorrect: "2" → Should be 6
Wait — perhaps the question means how many lines are explicitly drawn? But still, there are 6.
Alternatively, maybe they mean how many lines are named or used? But the question is clear: “How many lines appear in the figure?”
Given standard interpretation: 6 lines.
But let’s check the rest.
---
#### c) How many planes appear in the figure?
- This is a 2D figure (parallelogram), so it lies in one plane.
- All points are coplanar.
- ✔ Correct: 1
---
#### d) Name a line containing point F.
- Point $F$ is on diagonal $BD$.
- So line $BD$ contains $F$.
- Also, line $BF$, $FD$, or $BD$.
- ✔ "Line a" — if line $a = BD$, then yes.
- But need to know which line is labeled $a$.
- From diagram: line $a$ goes from $X$ to $Z$ — that’s diagonal $AC$.
- So line $a$ is $AC$, not $BD$.
- Then line $BD$ must be line $b$?
- Yes, if $a = AC$, $b = BD$, then $F$ is on $b$.
- So line $b$ contains $F$.
- But answer says "line a" → that’s wrong.
> ✘ Incorrect: "line a" → Should be line b
---
#### e) Name the intersection of lines a and b.
- Line $a$: $AC$, line $b$: $BD$
- They intersect at point $W$
- ✔ Correct: W
---
#### f) Give another name for line b.
- Line $b$ is $BD$, which passes through $Y$, $W$, $F$
- So could be called $\overleftrightarrow{YF}$, $\overleftrightarrow{YW}$, $\overleftrightarrow{DF}$, etc.
- Given answer: YF
- That’s acceptable — any two points on the line.
- ✔ Correct
---
#### g) Name three non-collinear points.
- Non-collinear: not on the same line.
- Example: $A$, $B$, $C$ — form triangle.
- Or $X$, $Y$, $Z$ — not collinear.
- Answer: $Y, Z, V$ — are these on same line?
- $Y$ on $BD$, $Z$ on $AC$, $V$ on $AD$ — not collinear.
- ✔ Likely correct.
---
#### h) Give another name for plane D.
- Plane $D$ is probably named after a point or set of points.
- But in diagram, no plane is labeled $D$ — wait, label says "plane D".
- Probably typo: maybe plane $XYZ$ or something.
- But answer says: plane XWR
- Points $X$, $W$, $R$: $X$ on $AC$, $W$ center, $R$ on $AD$
- Are they coplanar? Yes, all in the same plane.
- Since it’s a flat figure, all points lie in one plane.
- So any three non-collinear points define the plane.
- So plane $XWR$ is valid.
- ✔ Acceptable.
But the plane was called "plane D"? Maybe the plane is labeled $D$ in diagram? Not visible.
Assuming it’s just a name, so plane XWR is fine.
✔ Acceptable.
---
| Question | Student Answer | Correct? | Correction |
|--------|----------------|---------|------------|
| a) Points | 10 | ✘ | 11 |
| b) Lines | 2 | ✘ | 6 |
| c) Planes | 1 | ✔ | — |
| d) Line with F | line a | ✘ | line b |
| e) Intersection a & b | W | ✔ | — |
| f) Another name for line b | YF | ✔ | — |
| g) Non-collinear | Y,Z,V | ✔ | — |
| h) Another name for plane D | plane XWR | ✔ | — |
---
Diagram: Two rectangles (representing planes) overlapping, with lines crossing through them.
Points: $P, Q, R, S, T, U, V, N, M, O, X, Y$
Lines: $a, b, c, d$
Planes: $K, L$
#### a) How many points appear in the figure?
- Count: $P, Q, R, S, T, U, V, N, M, O, X, Y$ — that’s 12 points
- But student wrote 9 → too low.
> ✘ Incorrect: 9 → Should be 12
---
#### b) How many lines appear in the figure?
- Lines:
- $a$: $PQ$
- $b$: $RS$
- $c$: $TU$
- $d$: $MN$
- $XY$? Possibly
- Also $PO$, $QR$, etc.
- But clearly: $a, b, c, d$ — four lines
- And intersections suggest more, but only 4 are drawn.
- But answer says 3 → incorrect.
Wait: look again.
Lines shown:
- Line $a$: from $P$ to $Q$, extending
- Line $b$: from $R$ to $S$
- Line $c$: from $T$ to $U$
- Line $d$: from $M$ to $N$
- Also, $PO$ is part of line $a$?
Actually, lines $a$, $b$, $c$, $d$ are four distinct lines.
Answer says 3 → ✘ Incorrect
Should be 4
---
#### c) How many planes appear in the figure?
- Two rectangles: plane $K$ and plane $L$
- They intersect along a line
- ✔ Answer: 2 → ✔ Correct
---
#### d) Name three collinear points.
- Collinear: on same line
- $P, N, O$ — on line $a$?
- But $P$ and $N$ are on different lines?
- Wait: line $a$ goes through $P$, $N$, $O$?
- Diagram shows: line $a$ passes through $P$, $N$, $O$ — yes!
- So $P, N, O$ are collinear
- ✔ Answer: $P, N, O$ → ✔ Correct
---
#### e) Name four non-coplanar points.
- Non-coplanar: not all in the same plane
- Plane $K$: top rectangle
- Plane $L$: bottom rectangle
- So pick 2 from $K$, 2 from $L$ — e.g., $P, Q, M, N$
- But answer: $T, U, R, Q$
- $T, U$ on top plane ($K$), $R, Q$ on bottom plane ($L$)? Wait:
- $T, U$ on plane $K$
- $R$ on $b$, which crosses both?
- Actually, $R$ is on line $b$, which may pass through both planes.
- But $Q$ is on line $a$, which also crosses.
- So $T, U$ in plane $K$, $R, Q$ in plane $L$ → not all coplanar.
- So $T, U, R, Q$ are not coplanar → ✔ Valid.
✔ Correct
---
#### f) Give another name for line a.
- Line $a$ goes through $P, N, O$
- So could be called $\overleftrightarrow{PN}$, $\overleftrightarrow{NO}$, $\overleftrightarrow{PO}$
- Answer: MN → But $M$ and $N$ are on line $d$, not $a$
- Line $d$ is $MN$, so this is wrong.
> ✘ Incorrect: "MN" → Should be PO or PN or NO
---
#### g) Name the intersection of $\overline{PQ}$ and $\overline{MO}$
- $\overline{PQ}$: segment from $P$ to $Q$
- $\overline{MO}$: segment from $M$ to $O$
- They intersect at point $N$
- ✔ Answer: N → ✔ Correct
---
#### h) Name the intersection of plane K and line c
- Plane $K$: top plane
- Line $c$: from $T$ to $U$, lies entirely in plane $K$
- So intersection is the entire line $c$?
- But intersection of a plane and a line lying in it is the line itself.
- But usually, if the line is contained in the plane, the intersection is the line.
- But answer says S → that’s a point.
- $S$ is endpoint of line $b$, not on $c$
- Unless $c$ intersects plane $K$ at $S$ — but $S$ is not on $c$
Wait: line $c$ is $TU$, which is in plane $K$, so intersection is line $c$, not a point.
But answer says S → ✘ Incorrect
> ✘ Should be line c or segment TU
But if they want a point, maybe where it crosses? But it lies entirely in plane $K$
So answer S is wrong.
---
#### i) Give another name for plane L
- Plane $L$ is bottom plane
- Contains points $M, N, O, Q, R$
- So can be named by three non-collinear points: e.g., $MNO$, $MOR$, etc.
- Answer: plane NOK → $N, O, K$ — but $K$ is a plane, not a point!
Wait — $K$ is a point? No — in diagram, $K$ is labeled as a plane.
But $N, O, K$ — $K$ is not a point.
Possibly typo: maybe $N, O, Q$?
But answer says plane NOK — $K$ is not a point.
Unless $K$ is a point? But earlier, $K$ is labeled as a plane.
So plane NOK is invalid.
Correct would be plane MNO or plane NOQ
> ✘ Incorrect: "plane NOK" → Should be plane MNO or similar
---
#### j) Give another name for $\overline{PQ}$
- $\overline{PQ}$ is segment from $P$ to $Q$
- Could be called $\overline{QP}$
- But answer says line d — but line $d$ is $MN$, not $PQ$
- $PQ$ is line $a$
- So answer line d is wrong.
> ✘ Incorrect: "line d" → Should be line a or $\overline{QP}$
---
| Question | Student Answer | Correct? | Correction |
|--------|----------------|---------|------------|
| a) Points | 9 | ✘ | 12 |
| b) Lines | 3 | ✘ | 4 |
| c) Planes | 2 | ✔ | — |
| d) Collinear | P,N,O | ✔ | — |
| e) Non-coplanar | T,U,R,Q | ✔ | — |
| f) Another name for line a | MN | ✘ | PO or PN |
| g) Intersection PQ and MO | N | ✔ | — |
| h) Plane K ∩ line c | S | ✘ | line c or TU |
| i) Another name for plane L | plane NOK | ✘ | plane MNO |
| j) Another name for $\overline{PQ}$ | line d | ✘ | line a or $\overline{QP}$ |
---
Diagram: Cube or rectangular prism with vertices $A, B, C, D, E, F, G, H$
Points: $A, B, C, D, E, F, G, H$
Edges: 12 edges, but only some shown.
#### a) How many points appear in the figure?
- Vertices: $A, B, C, D, E, F, G, H$ → 8 points
- ✔ Answer: 8 → ✔ Correct
---
#### b) How many lines appear in the figure?
- Lines: edges of cube
- Each edge is a line segment
- Cube has 12 edges
- But answer says 9 → ✘ Incorrect
> ✘ Should be 12
But maybe only 9 are drawn? Let's see.
From diagram:
- $AB, BC, CD, DA$ — base
- $EF, FG, GH, HE$ — top
- $AE, BF, CG, DH$ — vertical
- But $AE$ is dashed, $CG$ might be missing?
Wait: in diagram, $E, F, G, H$ are top face
- $AE, BF, CG, DH$ — all seem present
- But $CG$ is dashed — still exists
- So 12 edges → 12 lines
But answer says 9 → ✘ Incorrect
---
#### c) How many planes appear in the figure?
- A cube has 6 faces → 6 planes
- But answer says 5 → ✘ Incorrect
> ✘ Should be 6
---
#### d) Name three collinear points.
- Collinear: on same straight line
- On a cube, no three vertices are collinear unless on an edge
- But edge has only two vertices
- So no three vertices are collinear
- But wait: $G, H, F$ — on top face, but not collinear
- $A, B, C$ — not collinear
- So no three vertices are collinear
- But the answer says: G, H, F — but $G, H, F$ form a triangle — not collinear
> ✘ Incorrect: G,H,F are not collinear
Maybe the diagram includes extensions? But in a cube, no three vertices are collinear.
Wait — maybe D, G, H? No — not on same line.
Unless the diagram shows a diagonal?
But no — all points are vertices.
So no three collinear points among vertices.
But answer says G, H, F → ✘ Incorrect
---
#### e) Name four coplanar points.
- Coplanar: lie in same plane
- Any face of cube has 4 coplanar points
- Example: $A, B, C, D$ (bottom face)
- Answer: $D, A, B, E$ — $D, A, B$ on bottom, $E$ above — not coplanar
- $E$ is not in plane $ABCD$
- So $D,A,B,E$ are not coplanar
> ✘ Incorrect: D,A,B,E → Not coplanar
Correct: $A,B,C,D$ or $E,F,G,H$ or $A,B,F,E$, etc.
---
#### f) Name the intersection of planes ABC and ABE
- Plane $ABC$: bottom face
- Plane $ABE$: front face (if $E$ is above $A$)
- Both contain points $A$ and $B$
- Their intersection is line $AB$
- ✔ Answer: AB → ✔ Correct
---
#### g) Name the intersection of planes BCH and DEF
- Plane $BCH$: points $B, C, H$
- $B, C$ on bottom, $H$ on top — so this is a side face
- Plane $DEF$: $D, E, F$
- $D$ on bottom, $E,F$ on top — this is another face
- Do they intersect?
- $BCH$: $B, C, H$
- $DEF$: $D, E, F$
- Shared point? $H$ and $F$? No.
- $C$ and $D$? Adjacent
- But no common point?
- Wait: $H$ is connected to $G$, $F$ to $G$, $C$ to $B$, $D$ to $A$
- $BCH$: $B-C-H$
- $DEF$: $D-E-F$
- Only possible shared point: none
- But $H$ and $F$ are adjacent, but not in both
- Wait: $C$ and $D$ are adjacent, but not in both
- So planes $BCH$ and $DEF$ do not intersect?
But answer says CF — line $CF$
Is $CF$ common to both?
- $C$ is in $BCH$, $F$ is in $DEF$
- But is $CF$ in both?
- $CF$ is a space diagonal — not on either face
Wait: $BCH$ — points $B, C, H$ — this is a face? $B, C, H$ — $H$ is above $D$, $C$ is corner, $B$ adjacent
- So $BCH$ is not a face — it’s a diagonal plane
- Similarly, $DEF$: $D, E, F$ — $D$ bottom-left-back, $E$ top-left-back, $F$ top-right-back — so this is a face (back face)
Similarly, $BCH$: $B$ bottom-front-right, $C$ bottom-back-right, $H$ top-back-left? Wait — labeling:
Standard cube labeling:
- Bottom: $A(0,0,0), B(1,0,0), C(1,1,0), D(0,1,0)$
- Top: $E(0,0,1), F(1,0,1), G(1,1,1), H(0,1,1)$
Then:
- Plane $BCH$: $B(1,0,0), C(1,1,0), H(0,1,1)$ — not a face
- Plane $DEF$: $D(0,1,0), E(0,0,1), F(1,0,1)$ — also not a face
But $DEF$: $D, E, F$ — not coplanar? $D(0,1,0), E(0,0,1), F(1,0,1)$ — yes, they are coplanar? Let’s see.
Actually, $DEF$ is not a face — the back face is $D, C, G, H$
Wait — maybe the labeling is different.
In diagram:
- $A, B, C, D$ bottom
- $E, F, G, H$ top
- $A$ to $E$, $B$ to $F$, $C$ to $G$, $D$ to $H$
So:
- $BCH$: $B, C, H$ — $B$ bottom-front-right, $C$ bottom-back-right, $H$ top-back-left
- $DEF$: $D, E, F$ — $D$ bottom-back-left, $E$ top-front-left, $F$ top-front-right
Now, do these planes intersect?
- $BCH$: $B, C, H$
- $DEF$: $D, E, F$
- Is there a common line?
Point $C$ and $D$ are adjacent, but not in both
- $F$ and $B$ are opposite
But $H$ and $D$ are connected — $HD$ is an edge
But $H$ in $BCH$, $D$ in $DEF$ — but $HD$ not in both
Wait — $C$ and $F$: $C$ in $BCH$, $F$ in $DEF$, but $CF$ is diagonal
But answer says CF
Let’s see if $CF$ is in both planes.
- $C$ and $F$ are in both planes?
- $C$ in $BCH$: yes
- $F$ in $DEF$: yes
- But is $CF$ in $BCH$? $BCH$ has $B, C, H$ — does it include $F$? No
- So $CF$ is not in $BCH$
So intersection cannot be $CF$
Perhaps the planes intersect at point $C$? But $C$ is not in $DEF$
Wait: $DEF$: $D, E, F$ — $C$ not in it
So no common point?
This suggests error.
But answer says CF — likely wrong.
Alternatively, maybe plane $BCH$ is meant to be $B, C, G$? But it says $BCH$
Or $DEF$ is $D, E, F$ — but $F$ is top-front-right
Wait — perhaps $BCH$ is $B, C, H$ — but $H$ is top-back-left
Then $BCH$ and $DEF$ may intersect at $C$ and $F$? No
No common points.
So answer CF is incorrect.
But maybe the planes intersect along line $CF$?
Unlikely.
Alternatively, maybe the planes are $BCH$ and $DEF$ — but $H$ and $D$ are both on left-back?
Wait — $D$ and $H$ are connected — $DH$ is an edge
But $D$ in $DEF$, $H$ in $BCH$
So if $BCH$ and $DEF$ share $H$ and $D$? But $D$ not in $BCH$
Only if $BCH$ includes $D$
But $BCH$ is $B, C, H$ — doesn’t include $D$
So no intersection?
This is problematic.
But answer says CF — likely incorrect.
---
#### h) Name the intersection of $\overline{AD}$ and $\overline{DF}$
- $\overline{AD}$: from $A$ to $D$ — bottom edge
- $\overline{DF}$: from $D$ to $F$ — diagonal?
- But $D$ to $F$: $D$ bottom-back-left, $F$ top-front-right — not adjacent
- In diagram, $DF$ may not be an edge
But $\overline{AD}$ and $\overline{DF}$ meet at $D$
So their intersection is point $D$
✔ Answer: D → ✔ Correct
---
| Question | Student Answer | Correct? | Correction |
|--------|----------------|---------|------------|
| a) Points | 8 | ✔ | — |
| b) Lines | 9 | ✘ | 12 |
| c) Planes | 5 | ✘ | 6 |
| d) Collinear | G,H,F | ✘ | No three collinear |
| e) Coplanar | D,A,B,E | ✘ | A,B,C,D or E,F,G,H |
| f) Intersection ABC and ABE | AB | ✔ | — |
| g) Intersection BCH and DEF | CF | ✘ | No clear intersection |
| h) Intersection AD and DF | D | ✔ | — |
---
#### Problem 1:
- a) 10 → 11
- b) 2 → 6
- d) line a → line b
- f) YF → correct
- h) plane XWR → acceptable
#### Problem 2:
- a) 9 → 12
- b) 3 → 4
- f) MN → PO or PN
- h) S → line c or TU
- i) plane NOK → plane MNO
- j) line d → line a
#### Problem 3:
- b) 9 → 12
- c) 5 → 6
- d) G,H,F → no three collinear
- e) D,A,B,E → A,B,C,D or E,F,G,H
- g) CF → incorrect, likely no intersection or different
---
- Review definitions: points, lines, planes, collinear, coplanar.
- Count carefully.
- Use proper notation.
- Be cautious with naming: use three non-collinear points for a plane.
Let me know if you'd like a corrected version of the worksheet!
---
Problem 1: Parallelogram with Diagonals
Diagram: A parallelogram $ABCD$ with diagonals $AC$ and $BD$ intersecting at point $W$. Points labeled: $X$, $Y$, $Z$, $F$, $V$, $T$, $P$, $R$, etc., along the sides and diagonals.
#### a) How many points appear in the figure?
- Count all labeled points: $A, B, C, D, W, X, Y, Z, F, V, T, P, R$
- But from diagram: $D, X, Y, Z, A, F, V, T, P, R, W$ — total of 11 points.
- ✔ Answer should be 11, not 10.
> ✘ Incorrect: "10" → Should be 11
---
#### b) How many lines appear in the figure?
- Lines shown:
- $AB$, $BC$, $CD$, $DA$ (sides)
- Diagonals: $AC$, $BD$
- So far: 6 lines
- But there are also segments like $XF$, $YZ$, etc., but those are parts of lines.
- However, in geometry, lines are infinite; line segments are finite.
- In this context, they’re likely asking for line segments or distinct lines drawn.
- But since it says “lines,” and only two diagonals and four sides are drawn as full lines, that’s 6 lines.
- But looking closely, the diagonals are drawn as lines through the center, so we have:
- Line $AC$ (passes through $X$, $W$, $Z$)
- Line $BD$ (passes through $Y$, $W$, $F$)
- Sides: $AB$, $BC$, $CD$, $DA$
- So 6 distinct lines.
- But answer is given as 2 → That’s incorrect.
> ✘ Incorrect: "2" → Should be 6
Wait — perhaps the question means how many lines are explicitly drawn? But still, there are 6.
Alternatively, maybe they mean how many lines are named or used? But the question is clear: “How many lines appear in the figure?”
Given standard interpretation: 6 lines.
But let’s check the rest.
---
#### c) How many planes appear in the figure?
- This is a 2D figure (parallelogram), so it lies in one plane.
- All points are coplanar.
- ✔ Correct: 1
---
#### d) Name a line containing point F.
- Point $F$ is on diagonal $BD$.
- So line $BD$ contains $F$.
- Also, line $BF$, $FD$, or $BD$.
- ✔ "Line a" — if line $a = BD$, then yes.
- But need to know which line is labeled $a$.
- From diagram: line $a$ goes from $X$ to $Z$ — that’s diagonal $AC$.
- So line $a$ is $AC$, not $BD$.
- Then line $BD$ must be line $b$?
- Yes, if $a = AC$, $b = BD$, then $F$ is on $b$.
- So line $b$ contains $F$.
- But answer says "line a" → that’s wrong.
> ✘ Incorrect: "line a" → Should be line b
---
#### e) Name the intersection of lines a and b.
- Line $a$: $AC$, line $b$: $BD$
- They intersect at point $W$
- ✔ Correct: W
---
#### f) Give another name for line b.
- Line $b$ is $BD$, which passes through $Y$, $W$, $F$
- So could be called $\overleftrightarrow{YF}$, $\overleftrightarrow{YW}$, $\overleftrightarrow{DF}$, etc.
- Given answer: YF
- That’s acceptable — any two points on the line.
- ✔ Correct
---
#### g) Name three non-collinear points.
- Non-collinear: not on the same line.
- Example: $A$, $B$, $C$ — form triangle.
- Or $X$, $Y$, $Z$ — not collinear.
- Answer: $Y, Z, V$ — are these on same line?
- $Y$ on $BD$, $Z$ on $AC$, $V$ on $AD$ — not collinear.
- ✔ Likely correct.
---
#### h) Give another name for plane D.
- Plane $D$ is probably named after a point or set of points.
- But in diagram, no plane is labeled $D$ — wait, label says "plane D".
- Probably typo: maybe plane $XYZ$ or something.
- But answer says: plane XWR
- Points $X$, $W$, $R$: $X$ on $AC$, $W$ center, $R$ on $AD$
- Are they coplanar? Yes, all in the same plane.
- Since it’s a flat figure, all points lie in one plane.
- So any three non-collinear points define the plane.
- So plane $XWR$ is valid.
- ✔ Acceptable.
But the plane was called "plane D"? Maybe the plane is labeled $D$ in diagram? Not visible.
Assuming it’s just a name, so plane XWR is fine.
✔ Acceptable.
---
✔ Summary for Problem 1:
| Question | Student Answer | Correct? | Correction |
|--------|----------------|---------|------------|
| a) Points | 10 | ✘ | 11 |
| b) Lines | 2 | ✘ | 6 |
| c) Planes | 1 | ✔ | — |
| d) Line with F | line a | ✘ | line b |
| e) Intersection a & b | W | ✔ | — |
| f) Another name for line b | YF | ✔ | — |
| g) Non-collinear | Y,Z,V | ✔ | — |
| h) Another name for plane D | plane XWR | ✔ | — |
---
Problem 2: Two Intersecting Planes
Diagram: Two rectangles (representing planes) overlapping, with lines crossing through them.
Points: $P, Q, R, S, T, U, V, N, M, O, X, Y$
Lines: $a, b, c, d$
Planes: $K, L$
#### a) How many points appear in the figure?
- Count: $P, Q, R, S, T, U, V, N, M, O, X, Y$ — that’s 12 points
- But student wrote 9 → too low.
> ✘ Incorrect: 9 → Should be 12
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#### b) How many lines appear in the figure?
- Lines:
- $a$: $PQ$
- $b$: $RS$
- $c$: $TU$
- $d$: $MN$
- $XY$? Possibly
- Also $PO$, $QR$, etc.
- But clearly: $a, b, c, d$ — four lines
- And intersections suggest more, but only 4 are drawn.
- But answer says 3 → incorrect.
Wait: look again.
Lines shown:
- Line $a$: from $P$ to $Q$, extending
- Line $b$: from $R$ to $S$
- Line $c$: from $T$ to $U$
- Line $d$: from $M$ to $N$
- Also, $PO$ is part of line $a$?
Actually, lines $a$, $b$, $c$, $d$ are four distinct lines.
Answer says 3 → ✘ Incorrect
Should be 4
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#### c) How many planes appear in the figure?
- Two rectangles: plane $K$ and plane $L$
- They intersect along a line
- ✔ Answer: 2 → ✔ Correct
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#### d) Name three collinear points.
- Collinear: on same line
- $P, N, O$ — on line $a$?
- But $P$ and $N$ are on different lines?
- Wait: line $a$ goes through $P$, $N$, $O$?
- Diagram shows: line $a$ passes through $P$, $N$, $O$ — yes!
- So $P, N, O$ are collinear
- ✔ Answer: $P, N, O$ → ✔ Correct
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#### e) Name four non-coplanar points.
- Non-coplanar: not all in the same plane
- Plane $K$: top rectangle
- Plane $L$: bottom rectangle
- So pick 2 from $K$, 2 from $L$ — e.g., $P, Q, M, N$
- But answer: $T, U, R, Q$
- $T, U$ on top plane ($K$), $R, Q$ on bottom plane ($L$)? Wait:
- $T, U$ on plane $K$
- $R$ on $b$, which crosses both?
- Actually, $R$ is on line $b$, which may pass through both planes.
- But $Q$ is on line $a$, which also crosses.
- So $T, U$ in plane $K$, $R, Q$ in plane $L$ → not all coplanar.
- So $T, U, R, Q$ are not coplanar → ✔ Valid.
✔ Correct
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#### f) Give another name for line a.
- Line $a$ goes through $P, N, O$
- So could be called $\overleftrightarrow{PN}$, $\overleftrightarrow{NO}$, $\overleftrightarrow{PO}$
- Answer: MN → But $M$ and $N$ are on line $d$, not $a$
- Line $d$ is $MN$, so this is wrong.
> ✘ Incorrect: "MN" → Should be PO or PN or NO
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#### g) Name the intersection of $\overline{PQ}$ and $\overline{MO}$
- $\overline{PQ}$: segment from $P$ to $Q$
- $\overline{MO}$: segment from $M$ to $O$
- They intersect at point $N$
- ✔ Answer: N → ✔ Correct
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#### h) Name the intersection of plane K and line c
- Plane $K$: top plane
- Line $c$: from $T$ to $U$, lies entirely in plane $K$
- So intersection is the entire line $c$?
- But intersection of a plane and a line lying in it is the line itself.
- But usually, if the line is contained in the plane, the intersection is the line.
- But answer says S → that’s a point.
- $S$ is endpoint of line $b$, not on $c$
- Unless $c$ intersects plane $K$ at $S$ — but $S$ is not on $c$
Wait: line $c$ is $TU$, which is in plane $K$, so intersection is line $c$, not a point.
But answer says S → ✘ Incorrect
> ✘ Should be line c or segment TU
But if they want a point, maybe where it crosses? But it lies entirely in plane $K$
So answer S is wrong.
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#### i) Give another name for plane L
- Plane $L$ is bottom plane
- Contains points $M, N, O, Q, R$
- So can be named by three non-collinear points: e.g., $MNO$, $MOR$, etc.
- Answer: plane NOK → $N, O, K$ — but $K$ is a plane, not a point!
Wait — $K$ is a point? No — in diagram, $K$ is labeled as a plane.
But $N, O, K$ — $K$ is not a point.
Possibly typo: maybe $N, O, Q$?
But answer says plane NOK — $K$ is not a point.
Unless $K$ is a point? But earlier, $K$ is labeled as a plane.
So plane NOK is invalid.
Correct would be plane MNO or plane NOQ
> ✘ Incorrect: "plane NOK" → Should be plane MNO or similar
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#### j) Give another name for $\overline{PQ}$
- $\overline{PQ}$ is segment from $P$ to $Q$
- Could be called $\overline{QP}$
- But answer says line d — but line $d$ is $MN$, not $PQ$
- $PQ$ is line $a$
- So answer line d is wrong.
> ✘ Incorrect: "line d" → Should be line a or $\overline{QP}$
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✔ Summary for Problem 2:
| Question | Student Answer | Correct? | Correction |
|--------|----------------|---------|------------|
| a) Points | 9 | ✘ | 12 |
| b) Lines | 3 | ✘ | 4 |
| c) Planes | 2 | ✔ | — |
| d) Collinear | P,N,O | ✔ | — |
| e) Non-coplanar | T,U,R,Q | ✔ | — |
| f) Another name for line a | MN | ✘ | PO or PN |
| g) Intersection PQ and MO | N | ✔ | — |
| h) Plane K ∩ line c | S | ✘ | line c or TU |
| i) Another name for plane L | plane NOK | ✘ | plane MNO |
| j) Another name for $\overline{PQ}$ | line d | ✘ | line a or $\overline{QP}$ |
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Problem 3: Cube-like Figure
Diagram: Cube or rectangular prism with vertices $A, B, C, D, E, F, G, H$
Points: $A, B, C, D, E, F, G, H$
Edges: 12 edges, but only some shown.
#### a) How many points appear in the figure?
- Vertices: $A, B, C, D, E, F, G, H$ → 8 points
- ✔ Answer: 8 → ✔ Correct
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#### b) How many lines appear in the figure?
- Lines: edges of cube
- Each edge is a line segment
- Cube has 12 edges
- But answer says 9 → ✘ Incorrect
> ✘ Should be 12
But maybe only 9 are drawn? Let's see.
From diagram:
- $AB, BC, CD, DA$ — base
- $EF, FG, GH, HE$ — top
- $AE, BF, CG, DH$ — vertical
- But $AE$ is dashed, $CG$ might be missing?
Wait: in diagram, $E, F, G, H$ are top face
- $AE, BF, CG, DH$ — all seem present
- But $CG$ is dashed — still exists
- So 12 edges → 12 lines
But answer says 9 → ✘ Incorrect
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#### c) How many planes appear in the figure?
- A cube has 6 faces → 6 planes
- But answer says 5 → ✘ Incorrect
> ✘ Should be 6
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#### d) Name three collinear points.
- Collinear: on same straight line
- On a cube, no three vertices are collinear unless on an edge
- But edge has only two vertices
- So no three vertices are collinear
- But wait: $G, H, F$ — on top face, but not collinear
- $A, B, C$ — not collinear
- So no three vertices are collinear
- But the answer says: G, H, F — but $G, H, F$ form a triangle — not collinear
> ✘ Incorrect: G,H,F are not collinear
Maybe the diagram includes extensions? But in a cube, no three vertices are collinear.
Wait — maybe D, G, H? No — not on same line.
Unless the diagram shows a diagonal?
But no — all points are vertices.
So no three collinear points among vertices.
But answer says G, H, F → ✘ Incorrect
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#### e) Name four coplanar points.
- Coplanar: lie in same plane
- Any face of cube has 4 coplanar points
- Example: $A, B, C, D$ (bottom face)
- Answer: $D, A, B, E$ — $D, A, B$ on bottom, $E$ above — not coplanar
- $E$ is not in plane $ABCD$
- So $D,A,B,E$ are not coplanar
> ✘ Incorrect: D,A,B,E → Not coplanar
Correct: $A,B,C,D$ or $E,F,G,H$ or $A,B,F,E$, etc.
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#### f) Name the intersection of planes ABC and ABE
- Plane $ABC$: bottom face
- Plane $ABE$: front face (if $E$ is above $A$)
- Both contain points $A$ and $B$
- Their intersection is line $AB$
- ✔ Answer: AB → ✔ Correct
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#### g) Name the intersection of planes BCH and DEF
- Plane $BCH$: points $B, C, H$
- $B, C$ on bottom, $H$ on top — so this is a side face
- Plane $DEF$: $D, E, F$
- $D$ on bottom, $E,F$ on top — this is another face
- Do they intersect?
- $BCH$: $B, C, H$
- $DEF$: $D, E, F$
- Shared point? $H$ and $F$? No.
- $C$ and $D$? Adjacent
- But no common point?
- Wait: $H$ is connected to $G$, $F$ to $G$, $C$ to $B$, $D$ to $A$
- $BCH$: $B-C-H$
- $DEF$: $D-E-F$
- Only possible shared point: none
- But $H$ and $F$ are adjacent, but not in both
- Wait: $C$ and $D$ are adjacent, but not in both
- So planes $BCH$ and $DEF$ do not intersect?
But answer says CF — line $CF$
Is $CF$ common to both?
- $C$ is in $BCH$, $F$ is in $DEF$
- But is $CF$ in both?
- $CF$ is a space diagonal — not on either face
Wait: $BCH$ — points $B, C, H$ — this is a face? $B, C, H$ — $H$ is above $D$, $C$ is corner, $B$ adjacent
- So $BCH$ is not a face — it’s a diagonal plane
- Similarly, $DEF$: $D, E, F$ — $D$ bottom-left-back, $E$ top-left-back, $F$ top-right-back — so this is a face (back face)
Similarly, $BCH$: $B$ bottom-front-right, $C$ bottom-back-right, $H$ top-back-left? Wait — labeling:
Standard cube labeling:
- Bottom: $A(0,0,0), B(1,0,0), C(1,1,0), D(0,1,0)$
- Top: $E(0,0,1), F(1,0,1), G(1,1,1), H(0,1,1)$
Then:
- Plane $BCH$: $B(1,0,0), C(1,1,0), H(0,1,1)$ — not a face
- Plane $DEF$: $D(0,1,0), E(0,0,1), F(1,0,1)$ — also not a face
But $DEF$: $D, E, F$ — not coplanar? $D(0,1,0), E(0,0,1), F(1,0,1)$ — yes, they are coplanar? Let’s see.
Actually, $DEF$ is not a face — the back face is $D, C, G, H$
Wait — maybe the labeling is different.
In diagram:
- $A, B, C, D$ bottom
- $E, F, G, H$ top
- $A$ to $E$, $B$ to $F$, $C$ to $G$, $D$ to $H$
So:
- $BCH$: $B, C, H$ — $B$ bottom-front-right, $C$ bottom-back-right, $H$ top-back-left
- $DEF$: $D, E, F$ — $D$ bottom-back-left, $E$ top-front-left, $F$ top-front-right
Now, do these planes intersect?
- $BCH$: $B, C, H$
- $DEF$: $D, E, F$
- Is there a common line?
Point $C$ and $D$ are adjacent, but not in both
- $F$ and $B$ are opposite
But $H$ and $D$ are connected — $HD$ is an edge
But $H$ in $BCH$, $D$ in $DEF$ — but $HD$ not in both
Wait — $C$ and $F$: $C$ in $BCH$, $F$ in $DEF$, but $CF$ is diagonal
But answer says CF
Let’s see if $CF$ is in both planes.
- $C$ and $F$ are in both planes?
- $C$ in $BCH$: yes
- $F$ in $DEF$: yes
- But is $CF$ in $BCH$? $BCH$ has $B, C, H$ — does it include $F$? No
- So $CF$ is not in $BCH$
So intersection cannot be $CF$
Perhaps the planes intersect at point $C$? But $C$ is not in $DEF$
Wait: $DEF$: $D, E, F$ — $C$ not in it
So no common point?
This suggests error.
But answer says CF — likely wrong.
Alternatively, maybe plane $BCH$ is meant to be $B, C, G$? But it says $BCH$
Or $DEF$ is $D, E, F$ — but $F$ is top-front-right
Wait — perhaps $BCH$ is $B, C, H$ — but $H$ is top-back-left
Then $BCH$ and $DEF$ may intersect at $C$ and $F$? No
No common points.
So answer CF is incorrect.
But maybe the planes intersect along line $CF$?
Unlikely.
Alternatively, maybe the planes are $BCH$ and $DEF$ — but $H$ and $D$ are both on left-back?
Wait — $D$ and $H$ are connected — $DH$ is an edge
But $D$ in $DEF$, $H$ in $BCH$
So if $BCH$ and $DEF$ share $H$ and $D$? But $D$ not in $BCH$
Only if $BCH$ includes $D$
But $BCH$ is $B, C, H$ — doesn’t include $D$
So no intersection?
This is problematic.
But answer says CF — likely incorrect.
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#### h) Name the intersection of $\overline{AD}$ and $\overline{DF}$
- $\overline{AD}$: from $A$ to $D$ — bottom edge
- $\overline{DF}$: from $D$ to $F$ — diagonal?
- But $D$ to $F$: $D$ bottom-back-left, $F$ top-front-right — not adjacent
- In diagram, $DF$ may not be an edge
But $\overline{AD}$ and $\overline{DF}$ meet at $D$
So their intersection is point $D$
✔ Answer: D → ✔ Correct
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✔ Summary for Problem 3:
| Question | Student Answer | Correct? | Correction |
|--------|----------------|---------|------------|
| a) Points | 8 | ✔ | — |
| b) Lines | 9 | ✘ | 12 |
| c) Planes | 5 | ✘ | 6 |
| d) Collinear | G,H,F | ✘ | No three collinear |
| e) Coplanar | D,A,B,E | ✘ | A,B,C,D or E,F,G,H |
| f) Intersection ABC and ABE | AB | ✔ | — |
| g) Intersection BCH and DEF | CF | ✘ | No clear intersection |
| h) Intersection AD and DF | D | ✔ | — |
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✔ Final Corrections Summary
#### Problem 1:
- a) 10 → 11
- b) 2 → 6
- d) line a → line b
- f) YF → correct
- h) plane XWR → acceptable
#### Problem 2:
- a) 9 → 12
- b) 3 → 4
- f) MN → PO or PN
- h) S → line c or TU
- i) plane NOK → plane MNO
- j) line d → line a
#### Problem 3:
- b) 9 → 12
- c) 5 → 6
- d) G,H,F → no three collinear
- e) D,A,B,E → A,B,C,D or E,F,G,H
- g) CF → incorrect, likely no intersection or different
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✔ Recommendations:
- Review definitions: points, lines, planes, collinear, coplanar.
- Count carefully.
- Use proper notation.
- Be cautious with naming: use three non-collinear points for a plane.
Let me know if you'd like a corrected version of the worksheet!
Parent Tip: Review the logic above to help your child master the concept of planes worksheet.