Question

A(r(t))=\pi(0.25+2t+4t^2)

Explanation:

To write a composite function, we apply one function to another given function. In this case, we want to find area in terms of time; this means that the function A(r) gets applied to the function r(t).

In order to do this, we replace r with r(t). We already know that r(t)=0.5+2t; this means we replace r with 0.5+2t:

A(r(t))=π(0.5+2t)²

To simplify this, we simplify the squared term:

A(r(t)) = π(0.5+2t)(0.5+2t)

A(r(t)) = π(0.5*0.5+0.5*2t+2t*0.5+2t*2t)

A(r(t)) = π(0.25+t+t+4t²)

A(r(t)) = π(0.25+2t+4t²)

Answer 1

So the composite function that gives the area of a circle in terms of time is:

A(r(t)) = π(0.25+2t+4t²)