Question

If the diameter of a semi-circular protractor is 14 cm, then find its perimeter.

Answer 1

Let AB be the diameter of the semi-circular protractor. 

So, `AB=14 cm`

`"We know that perimeter of the semicircle" = 1/2 (2pi r)+2r .........(1)`

We have given the diameter of the protractor.

Therefore, radius of the protractor =`14/2`

So, radius of the protractor `=7`

Substituting the value of r in equation (1) we get,

Perimeter of the semi-circular protractor=`1/2(2pxx7)+2xx7`

Perimeter of the semi-circular protractor=`(pixx7)+14`

Substituting `pi=22/7` we get

`"Perimeter of the semi-circular protractor"=(22/7xx7)+14`

`"Perimeter of the semi-circular protractor"=22+14`

`"Hence Perimeter of the semi-circular protractor"'=36` 

Therefore, perimeter of the semi-circular protractor is ` 36 cm`