Question

Find the surface area of the pyramid shown to the nearest whole number.

6 ft
5 ft
5 ft
Not drawn to scale
a. 85 A
b. 145 ft
c. 60 i
d. 25 ft

Answer 1

The answer is option A

Explanation:

Surface area of a pyramid =

area of base + area of triangular faces

Since it's a square based pyramid

It's surface area is

area of base + 4( area of one triangular face)

Since the square has equal sides

For square base

Area of a square = l²

where l is the length

From the question l = 5

So we have

Area of square base = 5² = 25ft²

For one of the triangular face

Area of a triangle = ½ × base × height

base = 5

height = 6

Area = ½ × 5 × 6 = 15ft²

So the surface area of the pyramid is

25 + 4(15)

= 25 + 60

We have the final answer as

Surface area = 85 ft²

Hope this helps you