The rotation axis is the straight line where one side of the rectangle is located, and the rotation body surrounded by the surface is called circular cylinder by rotating 360° on the other three sides, that is, one side of the AG rectangle is the axis, and the geometry obtained by rotating 360° is the cylinder.

PI r ² h o

area L = 2πrh

the bottom area T = B = PI r ²

area A = L + T + 2B  = 2 rh of PI + 2 ( PI r ² ) = 2 PI r (h + r)