Question

The drawing below (not to scale) shows a running track. The ends are semicircles. The distance between the two inner parallel straight lines is 60 meters, and they are each 100 meters long. The track is 10 meters wide.
Find the perimeter.

Answer 1

We are looking for the inner perimeter of the track. Since there are two semicircles, these mix to form one full circle so we can use the formula to find the circumference of the circle with a diameter of 60 m, which was given to us. With a diameter of 60m, the radius will be 30m. Now we can solve this problem.
C = 2πr
C = 2π(30)
C = 60π
The semicircle ends of the track are a distance of 60π m, and now we just need to add the lengths of the inner track which are 100 m each. So:
P = 60π + 100m + 100m
P = 200 + 60π
P = 388.5 m