Explain how to write a composite function to find the area of the region at time t.

Answer:

To write a composite function for the area at time t, you first identify the area formula as a function of the radius, A(r) = πr², and the radius as a function of time, r(t). Then, you substitute the expression for r(t) into the area formula in place of the variable r. This creates the composition A(r(t)), which can be written as A(r(t)) = π(r(t))².