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.

(A)Write and simplify an expression for the exact area of the sidewalk.

(B)Find the approximate area of the sidewalk. Use 3.14 to approximate π.

I don't want the answer, I just want to know how to get to the answer.....

Answer 1

A) the area of the sidewalk is the area of the big circle - area of small circle, so you would use the formula pi(r^2) to come up with a formula for each of the circles areas

b) you would just evaluate/calculate whatever you wrote for part A), substituting 3.14 for pi

lmk if you want to check your answer or if you're still stuck

Answer 2

A) This could be the expression pi(r^2)-pi(r^2)
11^2-9^2=40pi

B) 11^2-9^2=40*3.14=125.6m^2

Is this correct?

Answer 3

yeah that's good, just be sure to write

(pi)11^2 - (pi)9^2 = 40pi instead of just 11^2-9^2=40pi