The surface area of a torus doughnut is given by ruv 2cosuco

Solution

Below procedure is correct . this is a similar question to this . please substitute your equations inplace of these to get correct result . ThanQ An equation in Cartesian coordinates for a torus radially symmetric about the z-axis is (R - sqrt{x^2 + y^2})^2 + z^2 = r^2 and clearing the square root produces a quartic: (x^2+y^2+z^2 + R^2 - r^2)^2 = 4R^2(x^2+y^2) . The surface area and interior volume of this torus are given by A = 4 pi^2 R r = ( 2pi r ) ( 2 pi R ) V = 2 pi^2 R r^2 = ( pi r^2 ) ( 2pi R ). These formulas are the same as for a cylinder of length 2pR and radius r, created by cutting the tube and unrolling it by straightening out the line running around the center of the tube. The losses in surface area and volume on the inner side of the tube happen to exactly cancel out the gains on the outer side.