A spherical snowball is melting in the sun. It is noted that its surface area decreases at a rate of 3 c1112 / s at the moment when its diameter is g cm. The goal here is to determine the rate at which the diameter varies at that same moment. To solve this problem, let .7:- be the diameter of the snowball in cm, A its surface area in cm2 . and t the time in seconds (3). (a) Express A as a function of m . (The surface area is a formula you can find in your textbook.) A: .B cm2 dA (b) What is the value of d when a: = ? Give the exact value. m 7r dA dw : m cm . . . dw 6 . . (c) Using our prevrous results, give the (exact) value of a when a: = cm. Beware of signs, remember that the surface area of the snowball Is 1r decreasing with time! d2: a = a cm/s