Math CentralQuandaries & Queries


Question from Keith, a parent:

I am trying to help 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.


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

\[d + \frac{\pi}{2} d = 37.\]

Solve for $d.$

Write back if you need further assistance,

About Math Central


Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences.
Quandaries & Queries page Home page University of Regina PIMS