Question

If the lateral area of a square pyramid is 800 in² and the slant

height is 16 in, what is the length of the base edge?
a 30 in
b 25 in
C 21 in
d 32 in

Answer 1

b. 25 in

Explanation:

the lateral area is the area of the outside walls (not including the base area).

on a square pyramid there are 4 such outside walls in the form of triangles.

so, each such triangle has an area of 800/4 = 200 in².

the area of a triangle is

baseline × height / 2

the slant height is the height of a wall triangle (not the inner height of the pyramid).

a base edge is nothing else but the baseline of such a wall triangle.

so, we have

200 = baseline × 16 / 2 = baseline × 8

baseline = 200/8 = 25 in