Let's solve each of the surface area problems step by step. The image contains four different 3D shapes, and we are to find the
surface area of each.
---
1) Rectangular Prism (Net)
Given:
- Dimensions:
- Length = 10 in
- Width = 6 in
- Height = 4 in
This is a rectangular prism with a net shown. A rectangular prism has
6 faces: 2 of each type (top/bottom, front/back, left/right).
We calculate the area of each pair of faces:
-
Top & Bottom: $ 10 \times 6 = 60 $ in² → two of them → $ 2 \times 60 = 120 $
-
Front & Back: $ 10 \times 4 = 40 $ in² → two of them → $ 2 \times 40 = 80 $
-
Left & Right: $ 6 \times 4 = 24 $ in² → two of them → $ 2 \times 24 = 48 $
Now add all:
$$
\text{Surface Area} = 120 + 80 + 48 = \boxed{248} \text{ in}^2
$$
---
2) Another Rectangular Prism
Given:
- Dimensions:
- Length = 10 cm
- Width = 5 cm
- Height = 7 cm
Again, rectangular prism.
-
Top & Bottom: $ 10 \times 5 = 50 $ cm² → $ 2 \times 50 = 100 $
-
Front & Back: $ 10 \times 7 = 70 $ cm² → $ 2 \times 70 = 140 $
-
Left & Right: $ 5 \times 7 = 35 $ cm² → $ 2 \times 35 = 70 $
Total:
$$
\text{Surface Area} = 100 + 140 + 70 = \boxed{310} \text{ cm}^2
$$
---
3) Triangular Prism
Given:
- Triangle base: equilateral triangle with side = 10 ft
- Height of triangle: 8.7 ft
- Length (depth) of prism: 15 ft
A triangular prism has:
- 2 triangular bases
- 3 rectangular lateral faces
#### Step 1: Area of one triangular base
$$
\text{Area} = \frac{1}{2} \times \text{base} \times \text{height} = \frac{1}{2} \times 10 \times 8.7 = 43.5 \text{ ft}^2
$$
Two bases: $ 2 \times 43.5 = 87 $ ft²
#### Step 2: Lateral faces (rectangles)
Each rectangle has width = 10 ft (side of triangle), length = 15 ft
There are
three such rectangles:
$$
3 \times (10 \times 15) = 3 \times 150 = 450 \text{ ft}^2
$$
#### Total Surface Area:
$$
87 + 450 = \boxed{537} \text{ ft}^2
$$
---
4) Square Pyramid
Given:
- Base: square with side = 8 in
- Slant height = 5 in (from apex to midpoint of base edge)
A square pyramid has:
- 1 square base
- 4 triangular faces
#### Step 1: Area of base
$$
8 \times 8 = 64 \text{ in}^2
$$
#### Step 2: Area of one triangular face
Each triangle has:
- Base = 8 in
- Height = slant height = 5 in
$$
\text{Area} = \frac{1}{2} \times 8 \times 5 = 20 \text{ in}^2
$$
Four triangles: $ 4 \times 20 = 80 $ in²
#### Total Surface Area:
$$
64 + 80 = \boxed{144} \text{ in}^2
$$
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✔ Final Answers:
1)
248 in²
2)
310 cm²
3)
537 ft²
4)
144 in²
Let me know if you'd like this explained with diagrams or formulas!
Parent Tip: Review the logic above to help your child master the concept of finding surface area worksheet.