Answer:
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
