If the perimeter of a semi-circular protractor is 36 cm, find the diameter of the protractor.

22.8 approx.

We know, a protractor is in the shape of a semi-circle.
So, Perimeter of protractor = diameter + semi-arc
36 = 2r + πr
36 = r(2+π)
36 = r(2+22/7)
36 = r(36/7)
r = 36 x 7/36 
r = 7 cm
Diameter = 2r = 2x7 = 14 cm

Hope, it helps.
Thumbs up. :)

d=7