Question

A circular flower bed is 21 m in diameter and has a circular sidewalk around it that is 2 m wide. Find the area of the sidewalk in square meters. Use 3.14 for pi.
The area of the sidewalk is _____m x^{2}

Answer 1

The area of the sidewalk is 144.44 m².

The 2-m wide walk adds 4 m to the diameter, making it 21+4=25.

Since the radius is half the diameter, r = 25/2 = 12.5.

The area of the entire bed with walkway is 3.14(12.5)² = 490.625 m².

The diameter of the bed is 21, so the radius is 21/2 = 10.5.
The area of just the flower bed is 3.14(10.5)² = 346.185.

The difference between the two is 490.625-346.185 = 144.44 m².  This is the area of the walkway.