Answer
(a) $A=f(r)=\pi r^2$
(b) $f(0)=0$
(c) $f(r+1)=\pi(r+1)^2$.
(d) $f(r)+1=\pi r^2+1$.
(e) Centimeters.
Work Step by Step
(a) $A=f(r)=\pi r^2$
(b) $f(0)=0$
(c) $f(r+1)=\pi(r+1)^2$. This is the area of a circle whose radius is 1 cm more than $r$.
(d) $f(r)+1=\pi r^2+1$. This is the area of a circle of radius $r$, plus 1 square centimeter more.
(e) Centimeters.
