functions relations?

Question

A pebble is dropped into a cal pond, causing ripples in the form of concentric circles. The radius (in feet) of the outer ripple is r(t)=0.6t,where t is the time in seconds after the pebble strikes the water. The area of the circle is given by the function A(r) = pi r squared. Find and interpret (Aor)(t).

Answer 1

A(r(t)) = .36pit^2
This gives the area of the circle at any time t