an equilateral triangle whose perimeter= 36cm,is rotated about its side to form a closed solid figure.find the volume of the solid so formed.Explain please?

Side of the triangle = 12 cm

Two cones, each of height 6 cm and base radius 6√3 cm are formed.

Volume = 1/3 * pi * r^2 * h * 2 = 2/3 * pi * 36 * 3 * 6 = 36 * 12 pi = 432 pi cm^3

By rotating a side of an Equilateral triangle (any triangle), we will be getting a circular cone.
With the side as as height and radius.

Perimeter is 36cm, so each sides are 12cm.

Volume of cone = 1/3 pi r^2 h
1/3 * pi * 12^3 => 432 pi cm^3 is the answer.