The surface area of a cone with radius r and height h is given by the formula:a= pi r^2 + pi r sqr(pi ^2 + h^2) . A particular cone has a radius of 3 cm and a height of 8 cm. a) Use differentials to estimate how much the surface area would increase if only the radius was increased by 0.2 cm.b)Use differentials to estimate how much the surface area would increase if only the height was increased by 0.2 cm.