Aplane 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.

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.