Question

If x units are removed from the length of radius of circle , what is the number of units by which the circumference of the circle is deceased?

Answer 1

Let initially radius be r
and Final radius be r'

according to question

                           r' = r - x
Initially Circumference      
                          
                            C = 2 pi r

Final Circumference 
   
                            C' = 2 pi r'

putting the value of r'

                            C' = 2 pi (r-x)
                             C' = 2 pi r - 2 pi x
                              C' = C - 2 pi x

 Thus Circumference will get decreased by 2 pi x units