The perimeter of a semicircular protractor is 144cm, find the diameter

1.	The perimeter of a semicircular protractor is 144cm, find the diameter of the protractorTake Ď=
Answer» Perimeter of semicircle = (circumference of circle)/2 + Diameter of circle => P = 2πr/2 + 2r => 144 = (π + 2)r => 144 = 36/7 r => r = 144 x 7/36 = 28 cm Now Area of semicircle = πr^2/2 = 22/7 x 28 x 28 x 1/2 = 11 x 4 x 28 = 1232 sqcm

The perimeter of a semicircular protractor is 144cm, find the diameter of the protractorTake Ď=

Answer»

Perimeter of semicircle = (circumference of circle)/2 + Diameter of circle

=> P = 2πr/2 + 2r

=> 144 = (π + 2)r

=> 144 = 36/7 r

=> r = 144 x 7/36 = 28 cm

Now Area of semicircle = πr^2/2

= 22/7 x 28 x 28 x 1/2

= 11 x 4 x 28 = 1232 sqcm