A cube has a side of 18 cm. (a) Determine the radius of a sphere that has the same surface area as thecube. (b) Determine the radius of a sphere that has the same volume as the cube. The perimeter P of an ellipse with semi-minor axes a and b is given approximately by: (a) Determine the perimeter of an ellipse with a = 9 in.and b = 3 in. (b) An ellipse with b2a has a perimeter of P20 cm. Determine a and b.