Question

perimeter of semicircle protector is 108 cm find the diameter of protector

Answer 1

Let radius of the semicircle = r cm 

Perimeter of the  

semicircle = 2r + pi × r 

= ( 2 + pi )r 

= ( 2 + 22/ 7 ) r 

= [( 14 + 22 ) / 7 ] r  

P = 36r / 7 -----( 1 ) 

According to the problem given , 

P = 108 cm -----------( 2 ) 

( 1 ) = ( 2 ) 

36r/ 7 = 108 

r = ( 108 × 7 ) / 36 

r = 3 × 7 

r = 21 cm 

Therefore , 

Diameter of the semicircle = 2r 

d = 2 × 21 

d = 42 cm

Answer 2

Perimeter of semicircle = πr.
But it is given 108cm.
So,

ATQ, π r = 108cm.

or 22/7 × r =108cm

or r =(108 × 7 /22 )cm

Therefore r = 34.36cm [approx.]

So, Diameter = 2r = (2 ×34.36)cm=68.72cm