Try it on paper first. A hint, the key idea and the worked solution are here when you need them.
A bend on a race track is an arc of a circle of radius . The arc is long. Find the angle that the bend turns through at the centre of the circle. Take .
An arc that makes an angle at the centre has length . The perimeter of a sector is . In radians, .
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. , .
Step 1. The circumference. .
Step 2. The fraction. .
Step 3. The angle. We want , so .
Answer: .
Check. A quarter circle of radius has an arc of .
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