Question

a plane is passed through a parallelepiped, cutting all the lateral edges and forming a right section which is a square. If the lateral area of the solid is 216 cm^2 and a lateral edge measures 9 cm, find the measure of the one side of the section.

Answer 1

There are several information's already given in the question. Based on those given information's the answer can be easily deduced. 
Lateral area of the solid = 216 cm^2
Lateral edge of the solid = 9 cm
Let us assume the measure of the one side of the section = x
Then
216 = 4s * 9
216 = 36s
s = 6
From the above deduction, it can be concluded that the measure of the one side of the section is 6 cm. I hope that the answer has actually come to your help.