Question

the perimeter of a semicircular protractor is 108 cm find the diameter of the protractor

Answer 1

Heya....

Here's your answer.....

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

Thanks...!!!

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Sorry baby 'wink'

Answer 2

Hello friends!!

Here is your answer :

Perimeter of semicircular protractor = 108 cm

Let the radius of semi circle be r.

According to question,

$\pi r + 2r = 108$

$\\ Put \: \pi = \frac{22}{7}$

$\\ \frac{22}{7} \times r + 2r = 108$


$\\ r( \frac{22}{7} + 2) = 108$


$\\ r( \frac{22 + 14}{7} ) = 108$


$\\ r \times \frac{36}{7} = 108$


$\\ r = 108 \times \frac{7}{36}$


$r = 3 \times 7$


$r = 21$


Radius r of semicircular protractor = 21 cm

Diameter of semicircular protractor = 2 × r

= 2 × 21

= 42 cm


Therefore, required answer is 42 cm

Hope it helps you...