Question

The diagram shows a prism.

The cross section of the prism is a right-angled triangle.
The lengths of the sides of the triangle are 8 cm, 15 cm and 17 cm.
The length of the prism is 20 cm.
Work out the total surface area of the prism.
Diagram NOT
accurately drawn
8 cm
17 cm
20 cm
15 cm

Answer 1

Total surface area of the prism = 920 cm²

Explanation:

Given prism has 2 similar triangular surfaces and 3 rectangular surfaces of different dimensions.

Area of one triangular side =
`(1)/(2)(\text{Base})(\text{Height})`

Area of 2 similar sides = Base × Height

= 8 × 15

= 120 cm²

Area of rectangular side with dimensions 17cm × 20cm

Area of the side = 17 × 20 = 340 cm²

Area of the second rectangular side with dimensions 8cm × 20cm

Area of the side = 8 × 20 = 160 cm²

Area of third rectangular side with dimensions 20cm × 15cm

Area of the side = 20 × 15 = 300 cm²

Total surface area of the given triangular prism = 120 + 340 + 160 + 300

= 920 cm²