Question

A Gateway To (New Syllabus) Mathematics-D1
Q.6
The circular portions of the following figures
are semicircles. For each of the following
figures, find
its perimeter, (ii) its area.
Sol.
(a)
21 cm
36 cm​

Answer 1

Let r be the radius of the semi-circular protractor

Then the perimeter of the protractor is (πr+2r)=

7

36r

According to the problem

7

36r

=72

r=14

Now area of the protractor is

2

πr

2

=

7

11

×14×14

=22×14=308cm

2

Answer 2

I HOPE IT HELPFUL ANSWER.