How do you find the volume of a prism and a cylinder?

Volume of a cylinder is easy: Vol= [(pi) x radius^2] x height of cylinder] Where Pi= 3.1416 approx and radius = 1/2 of cylinder diameter The volume of a prism is complicated because it depends on the type of prism. for a regular shape prism the formula is : Vol = (area of base) x height If the prism is a "union" of differents shapes, you have to split the prism in smaller/single/easy shapes and calculate the volumes individually and then add the resulting volumes