ooooo CT-Mobile "3 10230 PM 9 sites.math.washington.edu 4 3. (14 points) The lateral surface area of a cone of radius r and height h (that is, the surface area excluding the base) is: A=7rrm d. (a) Find a formula (in terms of r and h) for -r for a cone With lateral surface area dh A = 157r cm2. (b) Evaluate the derivative of part (a) When 'r = 3 cm and h = 4 cm. (0) Suppose that the height of the cone decreases 0.1 cm (from 4.0 to 3.9 cm). Use differentials to approximate how much the radius must increase in order keep the lateral surface area of the cone constant. 'T'l'u: crank nF "(er