What is the surface area of the triangular prism?

[not drawn to scale]

54 square feet
67.5 square feet
81 square feet
85.5 square feet

The answer is the third

The surface area of prism = 81 ft²

Step-by-step explanation:

∵ The triangular prism has 5 faces

- Two triangles ⇒ bases

- 3 rectangles ⇒ side faces

* to find the surface area of it, we will find the area of

 each face and add them together

- Area of bases:

∵ The bases are right angle triangles with base 6 ft and height 4.5 ft

∵ Area triangle = 1/2 × base × height

∴ Area one base = 1/2 × 6 × 4.5 = 13.5 ft²

∴ Area two bases = 13.5 × 2 = 27 ft² ⇒ (1)

- Area of the first rectangle with dimensions 3 ft and 6 ft

∵ Area rectangle = L × W

∴ Area 1st rectangle = 3 × 6 = 18 ft² ⇒ (2)

- Area of the second rectangle with dimensions 3 ft and 7.5 ft

∴ Area 2nd rectangle = 3 × 7.5 = 22.5 ft² ⇒ (3)

- Area of the third rectangle with dimensions 3 ft and 4.5 ft

∴ Area 3rd rectangle = 3 × 4.5 = 13.5 ft² ⇒ (4)

Add (1) , (2) , (3) and (4)

∴ The surface area of prism = 27 + 18 + 22.5 + 13.5 = 81 ft²

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step-by-step explanation: