16Hit1600
Geometry and TrigonometryEasy–MediumRadius from the distance around a pond

Geometry and Trigonometry practice question

The distance around the edge of a circular pond is 10π metres. What is the radius of the pond, in metres?

Answer: 5

Circumference 2πr = 10π, so r = 5.

Common wrong answers

If you answered 10
10 is the diameter (or the circumference with π stripped off); the radius is half of that.
If you answered 25
25 is r², which would relate to the area, not the circumference.
If you answered 3.18
3.18 is 10/π, dividing by π as well as forgetting the 2.

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