The surface area of a regular pyramid with a square base which has a slant height of 5 units and base side lengths of 9 units is:
A) 360 units squared
B) 252 units squared.
C) 171 units squared.
D) 117 units squared.
Base area = area of a square = 9^2 = 81 units^2 (1)
Area of the sides = area of 4 trianges each with a base of 9 and height of 5 =
4* (1/2)(9)(5) = 90 units^2 (2)
Surface area = (1) + (2) = [ 81 + 90 ] = 171 units^2
+252 
