Question

16.
The diameter of a circle is 42 cm, find its perimeter. If the perimeter of the circle is

doubled, what will be the radius of the new circle.​

Answer 1

Answer:

Diameter of circle, d = 42 cm

Perimeter(circumference) of circle is given by "pi x d"

Therefore, C= 3.14 x 42 = 132 cm

Let C' = 2C

Then C' = 2 x 132 cm = 264 cm

>> 2 x pi x r = 264 cm

>> r = 264/(2 x 3.14)

>> r = 42 cm

Answer 2

Answer:

Perimeter of circle = 132 cm

Radius of new circle = 42 cm

Step-by-step explanation:

let,

diameter of circle = 42 cm

radius of circle = 42÷2 = 21 cm

Perimeter of Circle = 2πr

= 2 × 22/7 × 21

= 44 × 3

= 132 cm

Now, If the perimeter of circle is doubled i.e. 132+132 = 264 cm

Circumference\ Perimeter of new circle = 2πr

264 = 2 × 22/7 × r

r = 42 cm

Hope helpful...