Appendix A - Review - A.2 Geometry Essentials - A.2 Assess Your Understanding - Page A21: 50

$69\pi\approx216.77\ ft^2$ $26\pi\approx81.68\ ft$

1. The area of the deck is the difference between the areas of the two circles, thus $A=\pi r_2^2-\pi r_1^2=\pi((\frac{20}{2}+3)^2-(\frac{20}{2})^2)=\pi(169-100)=69\pi\approx216.77\ ft^2$ 2. The fence needed is the perimeter of the large circle, we have $P=\pi(20+6)=26\pi\approx81.68\ ft$