Question

If the radius of a circle is doubled, then, what is the change in its circumference?

Answer 1

If the radius is r, then its circumference of the circle is 2πr. 

If radius is doubled means r = 2r (new) 

Write r = 2r in 2πr. 

Then, the circumference = 2π x 2r 

= 4πr = 2.27πr 

Circumference is doubled. 

So, if the radius of a circle is doubled, then the circumference is also doubled.