If the perimeter of a semi-circular protractor is 36 cm, find the diameter of the protractor. (Take π = 22/7).

Given: Perimeter of semi-circular protractor = 36 cm

Now, perimeter of a semi-circle = πr + 2r , where r is the radius of the semi- circle.

∴ πr + 2r = 36

⇒ r(π + 2) = 36

⇒ r = 36/(π + 2)

=

=

= (36 × 7)/36

= 7

∴ Radius of the semi-circular protractor = 7 cm

Thus, diameter of the semi-circular protractor = 2r = 2 × 7 = 14 cm