Question

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

Answer 1

therefore perimeter of a semicircular protractor is πr+d
therefore 108= πr+d
therefore 108=πr+2r=r(π+2)
therefore 108/π+2=r

so, 108/(22/7+2)=r

or, 108/(22+14)/7=r

or, 108×7/36= r

or, 21=r
therefore d= 2× r
diameter is 2×21 =42

Answer 2

perimeter=108cm
pi*r+2r=108cm
r(22/7=2)=108cm
r(22+14/7)=108cm
r(36/7)=108cm
r=108*7/36
r=3*7
r=21cm
therefore,diameter=2r
=2*21=42cm
hope it  helps :)