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Triangular Prism Area Worksheets - Free Printable

Triangular Prism Area Worksheets

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Let’s solve each problem one by one. We’re finding the surface area of triangular prisms.

A triangular prism has:
- 2 identical triangular bases
- 3 rectangular sides

So, surface area = (area of triangle × 2) + (sum of areas of the 3 rectangles)

We’ll use:
- Area of triangle = (base × height) ÷ 2
- Area of rectangle = length × width

---

Problem 1:

Triangle base = 10 in, height = 8 in → area = (10 × 8)/2 = 40 in²
Two triangles: 40 × 2 = 80 in²

Rectangles:
- One is 10 in (length) × 10.63 in (side) → 10 × 10.63 = 106.3 in²
- Another is 10 in × 10.63 in → same = 106.3 in²
- Third is 10 in × 14 in → 10 × 14 = 140 in²

Wait — actually, looking at the diagram: the three rectangles are formed by the three sides of the triangle and the length of the prism (which is 14 in).

The triangle sides are: 10 in (base), and two slanted sides labeled 10.63 in each.

So the three rectangles are:
- 10 in × 14 in = 140 in²
- 10.63 in × 14 in = 148.82 in²
- 10.63 in × 14 in = 148.82 in²

Total rectangle area = 140 + 148.82 + 148.82 = 437.64 in²

Add triangles: 80 + 437.64 = 517.64 in²

But let me double-check — maybe the 14 in is the length of the prism, and the triangle’s sides are 10, 10.63, 10.63? Yes.

Alternatively, sometimes diagrams label the “height” of the triangle as perpendicular to base — which it is (8 in). So our triangle area is correct.

Final for #1: 517.64 in²

Wait — but let’s check if we can round or if numbers are exact. The 10.63 might be approximate. Let’s see: if triangle is isosceles with base 10, height 8, then each side is sqrt(5² + 8²) = sqrt(25+64)=sqrt(89)≈9.43 — wait, that doesn’t match 10.63.

Hold on — maybe I misread. In problem 1, the triangle has base 10 in, height 8 in, and the two other sides are labeled 10.63 in? That would mean it’s not a right triangle? But the height is drawn from apex to base, so it should split base into two 5s. Then side = sqrt(5² + 8²) = sqrt(25+64)=sqrt(89)≈9.43 — but diagram says 10.63. Hmm.

Wait — perhaps the 10.63 is the length of the rectangular face? No, in diagram 1, the 10.63 is written along the slant edge of the triangle.

Actually, looking again — in diagram 1, the triangle has:

- Base: 10 in
- Height: 8 in (perpendicular)
- Two equal sides: both labeled 10.63 in? That can’t be if height is 8 and half-base is 5 — because 5-8-? should be ~9.43.

Unless... maybe the 10.63 is NOT the side of the triangle, but the length of the rectangular face? Wait no — in the diagram, the 10.63 is written along the edge of the triangle.

Perhaps there's a mistake in my assumption. Let me recalculate using given numbers without questioning them — since this is homework, we use the numbers as given.

So for Problem 1:

Triangle area = (10 × 8)/2 = 40 → two triangles = 80

Rectangles:
- Rectangle 1: 10 in (triangle base) × 14 in (prism length) = 140
- Rectangle 2: 10.63 in × 14 in = 148.82
- Rectangle 3: 10.63 in × 14 in = 148.82

Sum rectangles: 140 + 148.82 + 148.82 = 437.64

Total SA = 80 + 437.64 = 517.64 in²

I think we go with that.

---

Problem 2:

Triangle: base 10 in, height 9 in → area = (10×9)/2 = 45 → two triangles = 90

Sides of triangle: one is 13.45 in (hypotenuse?), another is 10 in (base), and the third? Wait — it’s a right triangle? Diagram shows right angle at bottom left.

So legs: 9 in (height) and ? The base is 10 in, but is that the full base? Actually, in diagram 2, the triangle has:

- Vertical leg: 9 in
- Horizontal leg: ? Not labeled directly, but the hypotenuse is 13.45 in, and base of prism is 10 in? Wait — confusion.

Looking at diagram 2: the triangular face has:

- One side: 13.45 in (slanted)
- One side: 9 in (vertical, with right angle mark)
- The base of the triangle must be such that 9^2 + x^2 = 13.45^2

Calculate: 13.45² ≈ 180.9025, 9²=81, so x² = 180.9025 - 81 = 99.9025 → x ≈ 9.995 ≈ 10 in. Oh! So the horizontal leg is 10 in.

So triangle is right triangle with legs 9 in and 10 in, hypotenuse 13.45 in.

Area = (9×10)/2 = 45 → two triangles = 90

Now rectangles:

The prism length is 10 in (given at bottom).

Three rectangles correspond to the three sides of the triangle:

- Side 1: 9 in × 10 in (prism length) = 90
- Side 2: 10 in × 10 in = 100
- Side 3: 13.45 in × 10 in = 134.5

Sum rectangles: 90 + 100 + 134.5 = 324.5

Total SA = 90 + 324.5 = 414.5 in²

---

Problem 3:

Triangle: base 10 in, height 12.12 in → area = (10 × 12.12)/2 = 60.6 → two triangles = 121.2

Sides of triangle: two sides labeled 12.12 in? Wait — diagram shows:

- Base: 10 in
- Height: 12.12 in (perpendicular)
- Two slanted sides: both labeled 12.12 in? That would mean it’s equilateral? But base is 10, others 12.12 — possible.

Actually, if height is 12.12 and base 10, then each half-base is 5, so side = sqrt(5² + 12.12²) = sqrt(25 + 146.8944) = sqrt(171.8944) ≈ 13.11 — but diagram says 12.12. Contradiction.

Again, perhaps we just use given labels.

In diagram 3, the triangle has:

- Base: 10 in
- Height: 12.12 in (marked perpendicular)
- Two other sides: both labeled 12.12 in? Or is 12.12 the length of the rectangular face?

Looking carefully: in diagram 3, the number 12.12 is written along the slant edge of the triangle, and also the height is marked as 12.12? That can't be unless it's degenerate.

Wait — perhaps the 12.12 is the length of the prism? No, in diagram 3, the prism length is 16 in (at bottom).

Let me read the diagram again:

For problem 3:

- Triangular face: base 10 in, height 12.12 in (with right angle symbol), and the two equal sides are not labeled? Wait, no — in the image, the slant edges are labeled 12.12 in? Actually, upon closer inspection, in many of these, the number on the slant is the length of that edge.

But if height is 12.12 and base 10, then the slant side should be more than 12.12. Unless the height is not to the base? But it has a right angle mark to the base.

This is confusing. Perhaps in some diagrams, the "height" given is not the altitude, but a side? But in problem 1, it was clearly altitude.

Another idea: perhaps for all problems, the triangle's area is calculated using the given base and height (with right angle mark), and the other sides are given for the rectangles.

So for problem 3:

Triangle area = (base × height)/2 = (10 × 12.12)/2 = 60.6 → two triangles = 121.2

Prism length = 16 in

The three sides of the triangle are:

- Base: 10 in
- Left side: ? Not labeled, but in diagram, the left slant is labeled 12.12 in? Wait, in the user's image description, for problem 3, it says "12.12 in" on the left slant and "12.12 in" on the height? That doesn't make sense.

Perhaps I need to assume that the numbers given on the edges are the lengths for the rectangles.

Let's look at problem 3 as per standard interpretation:

From the diagram (as described in text):

- Triangle has base 10 in, height 12.12 in (altitude), so area = 60.6 per triangle.

- The two other sides of the triangle: since it's isosceles? With height 12.12 to base 10, then each half is 5, so side = sqrt(5^2 + 12.12^2) = sqrt(25 + 146.8944) = sqrt(171.8944) = 13.11 in approximately. But in the diagram, it's labeled as 12.12 in on the slant? That must be a mistake in my reading.

Perhaps in problem 3, the 12.12 is the length of the rectangular face, not the triangle side.

Let's try a different approach. In many textbooks, for triangular prisms, they give the three sides of the triangle and the length of the prism.

For problem 3:

Assume the triangle has sides: 10 in (base), and two sides of 12.12 in each? But then height would be sqrt(12.12^2 - 5^2) = sqrt(146.8944 - 25) = sqrt(121.8944) = 11.04 in, but diagram says height is 12.12 in. Inconsistency.

Perhaps the "12.12 in" written on the height is the altitude, and the "12.12 in" on the slant is a typo or something else.

To resolve this, let's calculate based on what makes sense.

In problem 3, if the triangle has base 10 in and height 12.12 in, then area is 60.6, and the two equal sides are each sqrt(5^2 + 12.12^2) = sqrt(25 + 146.8944) = sqrt(171.8944) = 13.11 in.

Then rectangles:

- 10 in × 16 in = 160
- 13.11 in × 16 in = 209.76
- 13.11 in × 16 in = 209.76

Sum rectangles = 160 + 209.76 + 209.76 = 579.52

Triangles: 121.2

Total SA = 121.2 + 579.52 = 700.72 in²

But the diagram might intend the slant sides to be 12.12 in, so let's try that.

If triangle sides are 10 in, 12.12 in, 12.12 in, then it's isosceles with base 10, equal sides 12.12.

Height h = sqrt(12.12^2 - 5^2) = sqrt(146.8944 - 25) = sqrt(121.8944) = 11.04 in

But in the diagram, the height is labeled as 12.12 in, which contradicts.

Perhaps the 12.12 on the height is a mistake, and it's 11.04, but we have to use given numbers.

I think for consistency, in all problems, the height given with right angle mark is the altitude, and the other numbers on the edges are the actual side lengths for the rectangles.

So for problem 3:

- Triangle: base 10 in, height 12.12 in → area = (10*12.12)/2 = 60.6 → two triangles = 121.2

- Sides of triangle: the two slant sides are not given numerically in a way that matches, but in the diagram, the left slant is labeled 12.12 in, and the right slant is also 12.12 in? Or is it the same as height?

Upon re-examining the user's input: for problem 3, it says "12.12 in" on the left slant and "12.12 in" on the height? That can't be.

Perhaps in problem 3, the "12.12 in" is the length of the prism? No, the prism length is 16 in.

I recall that in some diagrams, the number on the edge is the length for the rectangle.

Let's look at problem 4 for clue.

Problem 4: triangle base 10 in, height 10 in, slant sides 12.4 in and 12.4 in? And prism length 11 in.

If height is 10, base 10, then for isosceles, half-base 5, side = sqrt(5^2 + 10^2) = sqrt(25+100) = sqrt(125) = 11.18 in, but diagram says 12.4 in. Again inconsistency.

Perhaps the "height" given is not the altitude, but a side.

In problem 4, the right angle is at the bottom left, so it's a right triangle with legs 10 in and 10 in? Then hypotenuse = sqrt(10^2 + 10^2) = sqrt(200) = 14.14 in, but diagram says 12.4 in for the slant. Not matching.

This is frustrating. Perhaps for all problems, the triangle is right-angled, and the two legs are given, and the hypotenuse is calculated or given.

Let's list what is given for each problem based on common patterns.

After re-thinking, I found a better way: in each diagram, the triangular face has three sides labeled, and the length of the prism is given. The "height" with right angle mark is to help calculate area, but the side lengths are given for the rectangles.

For example, in problem 1:

- Triangle sides: 10 in (base), 10.63 in, 10.63 in
- Prism length: 14 in
- Height of triangle: 8 in (for area calculation)

So area of triangle = (base * height)/2 = (10*8)/2 = 40, even though with sides 10, 10.63, 10.63, the height should be sqrt(10.63^2 - 5^2) = sqrt(113.0 - 25) = sqrt(88) = 9.38, but it's given as 8. So we use the given height for area, and given side lengths for rectangles.

Similarly for others.

So for problem 1:

Triangles: 2 * (10*8/2) = 80

Rectangles:
- 10 * 14 = 140
- 10.63 * 14 = 148.82
- 10.63 * 14 = 148.82
Sum rect = 140 + 148.82 + 148.82 = 437.64
Total SA = 80 + 437.64 = 517.64 in²

For problem 2:

Triangle: base 10 in, height 9 in, so area = (10*9)/2 = 45, two triangles = 90

Sides of triangle: from diagram, the three sides are 9 in, 10 in, and 13.45 in (since it's right triangle with legs 9 and 10, hypotenuse 13.45)

Prism length: 10 in

Rectangles:
- 9 * 10 = 90
- 10 * 10 = 100
- 13.45 * 10 = 134.5
Sum rect = 90+100+134.5 = 324.5
Total SA = 90 + 324.5 = 414.5 in²

For problem 3:

Triangle: base 10 in, height 12.12 in, so area = (10*12.12)/2 = 60.6, two triangles = 121.2

Sides of triangle: the two slant sides are labeled 12.12 in each? In the diagram, it's shown as 12.12 on the left slant and 12.12 on the right slant? Or is it the same as height?

In the user's text, for problem 3: "12.12 in" on the left slant, "12.12 in" on the height, and "10 in" on base, "16 in" on prism length.

Perhaps the "12.12 in" on the slant is the length, and the "12.12 in" on the height is the altitude, but as before, it's inconsistent.

Maybe for problem 3, the triangle has sides 10 in, 12.12 in, and the third side is not given, but from the right angle, if height is 12.12 to base 10, then the two segments are 5 each, so sides are sqrt(5^2 + 12.12^2) = 13.11 in each.

But in the diagram, it's labeled as 12.12 on the slant, so perhaps it's a different configuration.

Another possibility: in problem 3, the "12.12 in" is the length of the rectangular face corresponding to the slant, but that doesn't help.

Let's assume that the number written on the edge of the triangle is the length of that edge, and the height with right angle is for area calculation, even if inconsistent.

So for problem 3:

- Triangle area = (10 * 12.12)/2 = 60.6 → 121.2 for two

- Sides: base 10 in, left side 12.12 in, right side 12.12 in (assuming isosceles)

- Prism length 16 in

Rectangles:
- 10 * 16 = 160
- 12.12 * 16 = 193.92
- 12.12 * 16 = 193.92
Sum rect = 160 + 193.92 + 193.92 = 547.84
Total SA = 121.2 + 547.84 = 669.04 in²

And ignore the inconsistency with height.

Similarly for others.

For problem 4:

Triangle: base 10 in, height 10 in, so area = (10*10)/2 = 50 → two triangles = 100

Sides: from diagram, left slant 12.4 in, right slant 12.4 in, base 10 in

Prism length 11 in

Rectangles:
- 10 * 11 = 110
- 12.4 * 11 = 136.4
- 12.4 * 11 = 136.4
Sum rect = 110 + 136.4 + 136.4 = 382.8
Total SA = 100 + 382.8 = 482.8 in²

For problem 5:

Triangle: base 8 in, height 12 in, so area = (8*12)/2 = 48 → two triangles = 96

Sides: left slant 14.4 in, right side 9 in, base 8 in

Prism length 9 in? Wait, in diagram 5, the prism length is 9 in (at bottom right).

Rectangles:
- 8 * 9 = 72
- 14.4 * 9 = 129.6
- 9 * 9 = 81
Sum rect = 72 + 129.6 + 81 = 282.6
Total SA = 96 + 282.6 = 378.6 in²

For problem 6:

Triangle: base 11 in, height 13 in, so area = (11*13)/2 = 71.5 → two triangles = 143

Sides: left side 13 in (vertical), base 11 in, right slant 17.11 in

Prism length 7 in

Rectangles:
- 13 * 7 = 91
- 11 * 7 = 77
- 17.11 * 7 = 119.77
Sum rect = 91 + 77 + 119.77 = 287.77
Total SA = 143 + 287.77 = 430.77 in²

Now, let's compile the answers:

1. 517.64 in²
2. 414.5 in²
3. 669.04 in²
4. 482.8 in²
5. 378.6 in²
6. 430.77 in²

But let's verify problem 3 again. If we use the height to calculate area, and the given side lengths for rectangles, and in problem 3, the sides are 10, 12.12, 12.12, then it's fine, even if the height doesn't match geometrically, because the problem gives us the height for area calculation.

Similarly for others.

So final answers:

1. 517.64
2. 414.5
3. 669.04
4. 482.8
5. 378.6
6. 430.77

All in square inches.

Now, to box the final answer as per instruction.

Since the user asked to solve the problem, and there are six problems, I'll provide all six answers.

Final Answer:
1. 517.64 in²
2. 414.5 in²
3. 669.04 in²
4. 482.8 in²
5. 378.6 in²
6. 430.77 in²
Parent Tip: Review the logic above to help your child master the concept of printable math worksheets surface area prism.
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