Question

At a zoo, the lion pen has a ring-shaped sidewalk around it. The outer edge of the sidewalk is a circle with a radius of 11 m. The inner edge of the sidewalk is a circle with a radius of 9 m.

(Q. 1)
Write and simplify an expression for the exact area of the sidewalk.
(Q. 2)
Find the approximate area of the sidewalk. Use 3.14 to approximate π.

Answer 1

Area of the sidewalk = Area of the whole circle - Area of the inner circle.

Area of the sidewalk = π(11)² - π(9)² = 40π

Answer: Area of the sidewalk = π(11)² - π(9)²

Area of the sidewalk = 40 x 3.14 = 125.6m²

Answer: 125.6m²