At the mission museum Mrs. Perez visited over break, there is a pond like the one below that has a ring shaped sidewalk around it. The outer edge of the sidewalk is a circle with a radius of 10 m. The inner edge of

the sidewalk is a circle with a radius of 8 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.

Question

Laura Kelly

Mathematics

25 July, 21:47

At the mission museum Mrs. Perez visited over break, there is a pond like the one below that has a ring shaped sidewalk around it. The outer edge of the sidewalk is a circle with a radius of 10 m. The inner edge of

the sidewalk is a circle with a radius of 8 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.

+1

Answers (1)

Know the Answer?

Gillian Powers · Answer 1

The formula for area of a circle is : A = PI x r^2

A) find the are of the two circles, subtract the two to find the area of the side walk:

Outside circle: A = PI x 10^2

Area = 100PI

Inner circle: A = PI x 8^2

Area = 64PI

Area of sidewalk:

100PI - 64 PI = 36PI

B) replace PI with 3.14:

Area = 36 x 3.14 = 113.04 square meters.