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 Question from Keith, a parent: I am trying to hlp my daughter I have the perimeter of a semi circle of 37 but how do I calculate the diameter from this. This is all the information I have. Help

Hi Keith,

The perimeter of a semicircle is made up of two parts, a diameter and a curved piece which has the length of half the circumference of the circle.

Suppose the diameter is $d$ units lang then you know that the circumference is $\pi d$ units long. Thus the perimeter of the semicircle is $d + \frac{\pi}{2} d$ units long. But you know that the perimeter is 37 units long so

$d + \frac{\pi}{2} d = 37.$

Solve for $d.$

Write back if you need further assistance,
Penny

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