A stone is thrown into a pond, creating a circular ripple that spreads over the pond in such a way that the radius is increasing at a rate of 3 ft/sec.
(a) Find a function r(t) for the radius in terms of t.
(b) Find a function A(t) for the area of the ripple in terms of the radius r.
(c) Find (Aor) (t). Explain the meaning of this function.