A circular flower bed is 24m in diameter and has a circular sidewalk around it that is 3m wide. Find the area of the sidewalk in square meters. Use 3.14 for .

Answer 1

Hey!

To begin, we're looking for area. Of what shape? A circle - hence the circular flower bed! Thus we have to know that the area of a circle is (pi)*r^2. (pi*r squared)

Be careful - we're looking for the area of the sidewalk! If we were to draw a picture to differentiate the two (flower bed and sidewalk), we would have a circle with what looks like a hole in the middle after shading the sidewalk. Hence, in order to find the area of the sidewalk, we need

Bigger Area minus Inside Area or

Area of Entire Circle - Area of Flower Bed.

You only need the two radii to begin working this out! Note that the radius of the entire circle is 24+6 (two 3 m strips) = 30/2 = 15. The radius of the flower bed is 24/2 = 12.

Let me know if you have questions!

Answer 2

24 inches in diameter means 12 meter radius

radius = 1/2 the diameter

Area = pi(r^2) = 144pi square meters

the Area of the sidewalk plus the flower bed is pi(12+3)^2 = 225pi

225pi - 144pi = 81pi square meters for the area of the sidewalk

answer: 81pi = about 81(3.14) = 254.34 m^2

more accurately 81(3.14159+) = 254.47 m^2 rounded off gives the same answer either way 254 m^2