Question

the perimetet of a semicircle is less by 20 cm than the perimeter of the circle what is the radius of the circle? ​

Answer 1

Perimeter of Circle = 2πr

Perimeter of semicircle = 2πr-20

Perimeter of semicircle = πr+2r

πr+2r = 2πr - 20

πr-2r = 20

r= 20*7/8 = 35/2 17.5 cm

So, the radius is 17.5 cm

Answer 2

Answer:

Step-by-step explanation:

Let Radius of circle=r

So perimeter of circle=2πr

Now, perimeter of semi-circle=πr+2r

Therefore, according to given statement

2πr-πr-2r=20

So, r(2π-π-2)=20

So, r=20/(π-2)

So, r=20×7/8

So, r=35/2=17.5cm

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