What is the area of the lateral surface of a rectangular regular pyramid if the side of the base is 3 and the total surface area is.

Given: regular quadrangular pyramid, base side 3, total surface area 27
Find: lateral surface area
Decision:
At the base of a regular quadrangular pyramid lies a square, from the given side of which is 3
So the base area is 3 ^ 2 = 9
Total surface area = base area + lateral surface area,
So lateral surface area = total surface area – base area
Lateral surface area = 27 – 9 = 18
Answer: 18.