Question

The pyramid shown has a square base that is 18 inches on each side. The slant height is 16 inches. What is the surface area of the pyramid?
A. 468 square inches

B. 900 square inches

C. 576 square inches

D. 1,728 square inches

Answer 1

The surface of the square pyramid is:

one square with a side length of 18 inches

four triangles with a base length of 18 inches and a height of 16 inches.

The area of a square: $A_\boxed{ }}=18^2=324\ in^2$

The area of a triangle: $A_\Delta=\dfrac{18\cdot16}{2}=144\ in^2$

The surface area of the pyramid is:

$SA=A_\boxed{ }}+4A_\Delta\\\\SA=324+4\cdot144=900\ in^2$

Answer: B. 900 square inches.