Prerequisites - P.4 - Factoring Polynomials - Exercises - Page 40: 81

$4\pi(r+1)$

Area of the outer circle with radius r+2 = $\pi(r+2)^2$ Area of the inner circle with radius r = $\pi(r)^2$ Subtract the area of the smaller circle from the area of the bigger circle to get the area of the shaded portion = $\pi(r+2)^2-$$\pi(r)^2$=$4r\pi+4\pi$