The formula C = 2√πA is designed to find a circle's circumference using the area (A). Alternatively, you can solve the equation A = πR2 in reverse to find R, then plug R into the circumference equation.
Explanation If ‘a’ represents his age today, and you have to find his age in four years you take 4 multiplied a. (4 x a) putting it together and you would get 4a
