help with precalculus..

Question

A pebble is dropped into a calm pond, causing ripples in the form of concentric circles. The radius (in feet) of the outermost ripple is given by r(t) = 0.3t,

 where t is time (in seconds) after the pebble strikes the water. The area of the circle is given by A(r) = 𝜋r².

 Find (A o r)(t).

(A o r)(t) =

Answer 1

(A ο r)(t) means A(r(t))

To determine what it is, plug in r(t) (which is "0.3t") into the function A in place of it's variable "r". In other words, write the function A but when you get to the variable "r", instead of writing "r", write what "r" is (which is "0.3t")

So (A ο r)(t) = π(0.3t)²

This can be simplified but I'll let you do that.