Question

Find the surface area of the right prism. Round to the nearest whole number.

Answer 1

`\large\boxed{S.A.=96\ cm^2}`

Explanation:

We have:

(1) two trapezoids with bases b₁ = 7cm and b₂ = 5cm and the height h = 4cm

(2) three rectangles 3 cm × 7 cm, 3 cm × 4 cm and 3 cm × 5 cm.

The formula of an area of a trapezoid:

`A=(b_1+b_2)/(2)\cdot h`

Substitute:

`A=(7+5)/(2)\cdot4=24\ cm^2`

Calculate the areas of the rectangles:

`A_1=(3)(7)=21\ cm^2\\\\A_2=(3)(4)=12\ cm^2\\\\A_3=(3)(5)=15\ cm^2`

The Surface Area:

`S.A.=(2)(24)+21+12+15=96\ cm^2`