Math worksheet for calculating area and perimeter of irregular shapes.
Geometry worksheet titled "Find the Area and Perimeter of Irregular Shapes" with eight problems involving rectangles and irregular polygons with labeled dimensions in yards, feet, and inches.
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Step-by-step solution for: Finding Area and Perimeter of Irregular shapes - Math Worksheets ...
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Show Answer Key & Explanations
Step-by-step solution for: Finding Area and Perimeter of Irregular shapes - Math Worksheets ...
Let’s solve each problem one by one. We’ll find the area and perimeter for each shape.
Remember:
- Perimeter = add up all the outside sides.
- Area = for rectangles, multiply length × width. For irregular shapes (like L-shapes), break them into rectangles, find each area, then add them.
---
Sides: 25 yd and 23 yd
→ Perimeter = 2 × (length + width) = 2 × (25 + 23) = 2 × 48 = 96 yd
→ Area = length × width = 25 × 23
Let’s calculate:
25 × 20 = 500
25 × 3 = 75
Total = 500 + 75 = 575 sq yd
✔ Check: 25×23 = 575 → correct.
---
Sides: 48 in and 24 in
→ Perimeter = 2 × (48 + 24) = 2 × 72 = 144 in
→ Area = 48 × 24
Break it down:
48 × 20 = 960
48 × 4 = 192
Total = 960 + 192 = 1152 sq in
✔ Check: 48×24 = 1152 → correct.
---
Given sides:
Left side = 12 ft
Bottom = 24 ft
Top right horizontal = 14 ft
Vertical step = 5 ft
We need to find missing sides to get perimeter and area.
First, let’s sketch mentally:
The full bottom is 24 ft. The top part has a horizontal segment of 14 ft on the right. So the left horizontal part must be 24 - 14 = 10 ft.
The total height on the left is 12 ft. There’s a vertical drop of 5 ft on the right side of the top rectangle. So the lower rectangle’s height is 12 - 5 = 7 ft.
Now we can split into two rectangles:
Rectangle A (top left): 10 ft wide × 5 ft high → Area = 10 × 5 = 50 sq ft
Rectangle B (bottom): 24 ft wide × 7 ft high → Area = 24 × 7 = 168 sq ft
Total Area = 50 + 168 = 218 sq ft
Perimeter: Walk around the outside.
Start at bottom left corner:
- Right along bottom: 24 ft
- Up right side: 7 ft (height of bottom rect)
- Left along top of bottom rect? Wait — no, better to trace outer edges only.
Actually, let’s list all outer sides:
From bottom left:
1. Right → 24 ft
2. Up → 7 ft (to start of inner corner)
3. Left → 14 ft? No — wait, after going up 7 ft, you go left? Actually, from bottom right, you go up 7 ft, then left 14 ft? That would be inside.
Better approach: Use the “outer path”.
Imagine walking around:
Start at bottom-left corner:
→ Go right 24 ft (bottom)
→ Go up 7 ft (right side of bottom rectangle)
→ Go left 14 ft (this is the top edge of the bottom rectangle? But that’s not outer — actually, after going up 7 ft, you’re at the inner corner. Then you go up another 5 ft? Let me re-draw mentally.
Actually, the shape looks like this:
```
+-------+
| | 5 ft
| A +-------+
| | B |
+-------+-------+
10 14
<------24------>
```
Height of A is 5 ft, height of B is 7 ft (since 12 - 5 = 7).
So outer perimeter:
Start at bottom-left:
1. Right → 24 ft
2. Up → 7 ft (right side of B)
3. Left → 14 ft (top of B) ← but this is NOT outer! Wait, no — after going up 7 ft, you are at the bottom-right of rectangle A? I’m confusing myself.
Alternative method: For any polygon, perimeter is sum of all outer sides. Given labeled sides:
Labeled: 12 ft (left), 5 ft (inner vertical), 14 ft (inner horizontal), 24 ft (bottom)
Missing sides:
- Top horizontal: since bottom is 24, and the right part is 14, the left top must be 24 - 14 = 10 ft
- Right vertical: total height is 12 ft, and the top part is 5 ft, so the bottom part is 12 - 5 = 7 ft
Now, trace the outline:
Start at bottom-left:
→ Right 24 ft (bottom)
→ Up 7 ft (right side of lower part)
→ Left 14 ft (this is the top of the lower rectangle — but is this outer? Actually, no — because above it is the upper rectangle. Wait, in an L-shape, when you go up 7 ft on the right, then you turn left and go 14 ft — but that 14 ft is actually the *bottom* of the upper rectangle? I think I have the orientation wrong.
Let me define coordinates to avoid confusion.
Place bottom-left corner at (0,0)
Then:
- Bottom goes to (24, 0)
- From (24,0) go up to (24, 7) [since lower height is 7]
- Then left to (10, 7) [because 24 - 14 = 10]
- Then up to (10, 12) [since total height is 12]
- Then left to (0,12)
- Then down to (0,0)
Yes! That makes sense.
So the vertices are:
(0,0) → (24,0) → (24,7) → (10,7) → (10,12) → (0,12) → back to (0,0)
Now, compute distances between consecutive points:
1. (0,0) to (24,0): 24 ft
2. (24,0) to (24,7): 7 ft
3. (24,7) to (10,7): 14 ft (since 24-10=14)
4. (10,7) to (10,12): 5 ft
5. (10,12) to (0,12): 10 ft
6. (0,12) to (0,0): 12 ft
Add them: 24 + 7 + 14 + 5 + 10 + 12 = let's add:
24+7=31; 31+14=45; 45+5=50; 50+10=60; 60+12=72 ft
So perimeter = 72 ft
Area: as before, two rectangles:
- Lower: 24 ft × 7 ft = 168 sq ft
- Upper: 10 ft × 5 ft = 50 sq ft
Total = 168 + 50 = 218 sq ft
✔ Matches earlier calculation.
---
Given:
Left side = 11 ft
Bottom = 29 ft
Right horizontal = 17 ft
Inner vertical = 7 ft
Find missing sides.
Total bottom = 29 ft. Right part is 17 ft, so left top horizontal = 29 - 17 = 12 ft
Total height = 11 ft. Inner vertical is 7 ft, so lower rectangle height = 11 - 7 = 4 ft
Split into two rectangles:
Upper left: 12 ft × 7 ft → Area = 12 × 7 = 84 sq ft
Lower: 29 ft × 4 ft → Area = 29 × 4 = 116 sq ft
Total Area = 84 + 116 = 200 sq ft
Perimeter: use coordinate method again.
Vertices:
Start at (0,0)
→ (29,0) → (29,4) → (12,4) → (12,11) → (0,11) → (0,0)
Distances:
1. (0,0)-(29,0): 29
2. (29,0)-(29,4): 4
3. (29,4)-(12,4): 17 (29-12=17)
4. (12,4)-(12,11): 7
5. (12,11)-(0,11): 12
6. (0,11)-(0,0): 11
Sum: 29+4=33; +17=50; +7=57; +12=69; +11=80 ft
Perimeter = 80 ft
✔ Check: 29+4+17+7+12+11 = 80 → correct.
---
Sides: 32 ft and 11 ft
Perimeter = 2 × (32 + 11) = 2 × 43 = 86 ft
Area = 32 × 11 = 32 × 10 + 32 × 1 = 320 + 32 = 352 sq ft
✔ Correct.
---
Sides: 27 ft and 13 ft
Perimeter = 2 × (27 + 13) = 2 × 40 = 80 ft
Area = 27 × 13
27 × 10 = 270
27 × 3 = 81
Total = 270 + 81 = 351 sq ft
✔ Correct.
---
Sides: 23 yd and 21 yd
Perimeter = 2 × (23 + 21) = 2 × 44 = 88 yd
Area = 23 × 21
23 × 20 = 460
23 × 1 = 23
Total = 460 + 23 = 483 sq yd
✔ Correct.
---
Given:
Left side = 18 ft
Bottom = 28 ft
Right horizontal = 14 ft
Inner vertical = 11 ft
Find missing sides.
Total bottom = 28 ft. Right part is 14 ft, so left top horizontal = 28 - 14 = 14 ft
Total height = 18 ft. Inner vertical is 11 ft, so lower rectangle height = 18 - 11 = 7 ft
Split into two rectangles:
Upper left: 14 ft × 11 ft → Area = 14 × 11 = 154 sq ft
Lower: 28 ft × 7 ft → Area = 28 × 7 = 196 sq ft
Total Area = 154 + 196 = 350 sq ft
Perimeter: coordinates.
Vertices:
(0,0) → (28,0) → (28,7) → (14,7) → (14,18) → (0,18) → (0,0)
Distances:
1. (0,0)-(28,0): 28
2. (28,0)-(28,7): 7
3. (28,7)-(14,7): 14 (28-14=14)
4. (14,7)-(14,18): 11
5. (14,18)-(0,18): 14
6. (0,18)-(0,0): 18
Sum: 28+7=35; +14=49; +11=60; +14=74; +18=92 ft
Perimeter = 92 ft
✔ Check: 28+7+14+11+14+18 = 92 → correct.
---
Final Answer:
1. Perimeter: 96 yd, Area: 575 sq yd
2. Perimeter: 144 in, Area: 1152 sq in
3. Perimeter: 72 ft, Area: 218 sq ft
4. Perimeter: 80 ft, Area: 200 sq ft
5. Perimeter: 86 ft, Area: 352 sq ft
6. Perimeter: 80 ft, Area: 351 sq ft
7. Perimeter: 88 yd, Area: 483 sq yd
8. Perimeter: 92 ft, Area: 350 sq ft
Remember:
- Perimeter = add up all the outside sides.
- Area = for rectangles, multiply length × width. For irregular shapes (like L-shapes), break them into rectangles, find each area, then add them.
---
Problem 1: Rectangle
Sides: 25 yd and 23 yd
→ Perimeter = 2 × (length + width) = 2 × (25 + 23) = 2 × 48 = 96 yd
→ Area = length × width = 25 × 23
Let’s calculate:
25 × 20 = 500
25 × 3 = 75
Total = 500 + 75 = 575 sq yd
✔ Check: 25×23 = 575 → correct.
---
Problem 2: Rectangle
Sides: 48 in and 24 in
→ Perimeter = 2 × (48 + 24) = 2 × 72 = 144 in
→ Area = 48 × 24
Break it down:
48 × 20 = 960
48 × 4 = 192
Total = 960 + 192 = 1152 sq in
✔ Check: 48×24 = 1152 → correct.
---
Problem 3: L-shaped figure
Given sides:
Left side = 12 ft
Bottom = 24 ft
Top right horizontal = 14 ft
Vertical step = 5 ft
We need to find missing sides to get perimeter and area.
First, let’s sketch mentally:
The full bottom is 24 ft. The top part has a horizontal segment of 14 ft on the right. So the left horizontal part must be 24 - 14 = 10 ft.
The total height on the left is 12 ft. There’s a vertical drop of 5 ft on the right side of the top rectangle. So the lower rectangle’s height is 12 - 5 = 7 ft.
Now we can split into two rectangles:
Rectangle A (top left): 10 ft wide × 5 ft high → Area = 10 × 5 = 50 sq ft
Rectangle B (bottom): 24 ft wide × 7 ft high → Area = 24 × 7 = 168 sq ft
Total Area = 50 + 168 = 218 sq ft
Perimeter: Walk around the outside.
Start at bottom left corner:
- Right along bottom: 24 ft
- Up right side: 7 ft (height of bottom rect)
- Left along top of bottom rect? Wait — no, better to trace outer edges only.
Actually, let’s list all outer sides:
From bottom left:
1. Right → 24 ft
2. Up → 7 ft (to start of inner corner)
3. Left → 14 ft? No — wait, after going up 7 ft, you go left? Actually, from bottom right, you go up 7 ft, then left 14 ft? That would be inside.
Better approach: Use the “outer path”.
Imagine walking around:
Start at bottom-left corner:
→ Go right 24 ft (bottom)
→ Go up 7 ft (right side of bottom rectangle)
→ Go left 14 ft (this is the top edge of the bottom rectangle? But that’s not outer — actually, after going up 7 ft, you’re at the inner corner. Then you go up another 5 ft? Let me re-draw mentally.
Actually, the shape looks like this:
```
+-------+
| | 5 ft
| A +-------+
| | B |
+-------+-------+
10 14
<------24------>
```
Height of A is 5 ft, height of B is 7 ft (since 12 - 5 = 7).
So outer perimeter:
Start at bottom-left:
1. Right → 24 ft
2. Up → 7 ft (right side of B)
3. Left → 14 ft (top of B) ← but this is NOT outer! Wait, no — after going up 7 ft, you are at the bottom-right of rectangle A? I’m confusing myself.
Alternative method: For any polygon, perimeter is sum of all outer sides. Given labeled sides:
Labeled: 12 ft (left), 5 ft (inner vertical), 14 ft (inner horizontal), 24 ft (bottom)
Missing sides:
- Top horizontal: since bottom is 24, and the right part is 14, the left top must be 24 - 14 = 10 ft
- Right vertical: total height is 12 ft, and the top part is 5 ft, so the bottom part is 12 - 5 = 7 ft
Now, trace the outline:
Start at bottom-left:
→ Right 24 ft (bottom)
→ Up 7 ft (right side of lower part)
→ Left 14 ft (this is the top of the lower rectangle — but is this outer? Actually, no — because above it is the upper rectangle. Wait, in an L-shape, when you go up 7 ft on the right, then you turn left and go 14 ft — but that 14 ft is actually the *bottom* of the upper rectangle? I think I have the orientation wrong.
Let me define coordinates to avoid confusion.
Place bottom-left corner at (0,0)
Then:
- Bottom goes to (24, 0)
- From (24,0) go up to (24, 7) [since lower height is 7]
- Then left to (10, 7) [because 24 - 14 = 10]
- Then up to (10, 12) [since total height is 12]
- Then left to (0,12)
- Then down to (0,0)
Yes! That makes sense.
So the vertices are:
(0,0) → (24,0) → (24,7) → (10,7) → (10,12) → (0,12) → back to (0,0)
Now, compute distances between consecutive points:
1. (0,0) to (24,0): 24 ft
2. (24,0) to (24,7): 7 ft
3. (24,7) to (10,7): 14 ft (since 24-10=14)
4. (10,7) to (10,12): 5 ft
5. (10,12) to (0,12): 10 ft
6. (0,12) to (0,0): 12 ft
Add them: 24 + 7 + 14 + 5 + 10 + 12 = let's add:
24+7=31; 31+14=45; 45+5=50; 50+10=60; 60+12=72 ft
So perimeter = 72 ft
Area: as before, two rectangles:
- Lower: 24 ft × 7 ft = 168 sq ft
- Upper: 10 ft × 5 ft = 50 sq ft
Total = 168 + 50 = 218 sq ft
✔ Matches earlier calculation.
---
Problem 4: Another L-shape
Given:
Left side = 11 ft
Bottom = 29 ft
Right horizontal = 17 ft
Inner vertical = 7 ft
Find missing sides.
Total bottom = 29 ft. Right part is 17 ft, so left top horizontal = 29 - 17 = 12 ft
Total height = 11 ft. Inner vertical is 7 ft, so lower rectangle height = 11 - 7 = 4 ft
Split into two rectangles:
Upper left: 12 ft × 7 ft → Area = 12 × 7 = 84 sq ft
Lower: 29 ft × 4 ft → Area = 29 × 4 = 116 sq ft
Total Area = 84 + 116 = 200 sq ft
Perimeter: use coordinate method again.
Vertices:
Start at (0,0)
→ (29,0) → (29,4) → (12,4) → (12,11) → (0,11) → (0,0)
Distances:
1. (0,0)-(29,0): 29
2. (29,0)-(29,4): 4
3. (29,4)-(12,4): 17 (29-12=17)
4. (12,4)-(12,11): 7
5. (12,11)-(0,11): 12
6. (0,11)-(0,0): 11
Sum: 29+4=33; +17=50; +7=57; +12=69; +11=80 ft
Perimeter = 80 ft
✔ Check: 29+4+17+7+12+11 = 80 → correct.
---
Problem 5: Rectangle
Sides: 32 ft and 11 ft
Perimeter = 2 × (32 + 11) = 2 × 43 = 86 ft
Area = 32 × 11 = 32 × 10 + 32 × 1 = 320 + 32 = 352 sq ft
✔ Correct.
---
Problem 6: Rectangle
Sides: 27 ft and 13 ft
Perimeter = 2 × (27 + 13) = 2 × 40 = 80 ft
Area = 27 × 13
27 × 10 = 270
27 × 3 = 81
Total = 270 + 81 = 351 sq ft
✔ Correct.
---
Problem 7: Rectangle
Sides: 23 yd and 21 yd
Perimeter = 2 × (23 + 21) = 2 × 44 = 88 yd
Area = 23 × 21
23 × 20 = 460
23 × 1 = 23
Total = 460 + 23 = 483 sq yd
✔ Correct.
---
Problem 8: L-shape
Given:
Left side = 18 ft
Bottom = 28 ft
Right horizontal = 14 ft
Inner vertical = 11 ft
Find missing sides.
Total bottom = 28 ft. Right part is 14 ft, so left top horizontal = 28 - 14 = 14 ft
Total height = 18 ft. Inner vertical is 11 ft, so lower rectangle height = 18 - 11 = 7 ft
Split into two rectangles:
Upper left: 14 ft × 11 ft → Area = 14 × 11 = 154 sq ft
Lower: 28 ft × 7 ft → Area = 28 × 7 = 196 sq ft
Total Area = 154 + 196 = 350 sq ft
Perimeter: coordinates.
Vertices:
(0,0) → (28,0) → (28,7) → (14,7) → (14,18) → (0,18) → (0,0)
Distances:
1. (0,0)-(28,0): 28
2. (28,0)-(28,7): 7
3. (28,7)-(14,7): 14 (28-14=14)
4. (14,7)-(14,18): 11
5. (14,18)-(0,18): 14
6. (0,18)-(0,0): 18
Sum: 28+7=35; +14=49; +11=60; +14=74; +18=92 ft
Perimeter = 92 ft
✔ Check: 28+7+14+11+14+18 = 92 → correct.
---
Final Answer:
1. Perimeter: 96 yd, Area: 575 sq yd
2. Perimeter: 144 in, Area: 1152 sq in
3. Perimeter: 72 ft, Area: 218 sq ft
4. Perimeter: 80 ft, Area: 200 sq ft
5. Perimeter: 86 ft, Area: 352 sq ft
6. Perimeter: 80 ft, Area: 351 sq ft
7. Perimeter: 88 yd, Area: 483 sq yd
8. Perimeter: 92 ft, Area: 350 sq ft
Parent Tip: Review the logic above to help your child master the concept of finding volume of irregular shapes worksheet.