Question

Sarah is designing a triangular pyramid made of all glass to go on top of a building. All of the faces of the pyramid have a height of 17 feet and a base of 20 feet.



Note: Figure is not drawn to scale.

How much glass is needed?
A.
2,040 sq ft
B.
1,360 sq ft
C.
680 sq ft
D.
340 sq ft

Answer 1

Each triangular face area = 1/2 · base · height = 1/2 · 20 · 17 = 170 sq ft.
A triangular pyramid has 4 faces, so total glass = 4 · 170 = 680 sq ft.

Answer: C (680 sq ft)