Question

If the perimeter of a semi-circular protractor is 108 cm, find the diameter of the protractor.

Answer 1

Let the radius of the protractor be r cm. Then,

Perimeter = 108 cm

$\frac{1}{2}\left(2\pi r\right)+2r=108$

$\pi r+2r=108$

$\frac{22}{7}\times r+2r=108$

$r=21$

Diameter of protractor = $2r=42$ $cm$