Math CentralQuandaries & Queries


Question from Lisa, a student:

How do you find the perimeter of a semi circle when you are only given the diameter, say 24 units?

Hi Lisa,

The perimeter of a circle is π × d where d is the diameter so half of that is 1/2 π × d. But If you are going to walk around a semicircle you need to go half way around the circle and then across a diagonal to get back to where you started so the perimeter is 1/2 π × d + d.


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