### Theory:

Chennai corporation has planned to establish a new park with the children in a circular shape. For protection, they schemed to build a wall around the park as well. But to build the wall, first, they should know the length of the wall. So the question is how they can find the length of the wall?

Circumference of circle $$=$$ $\mathrm{\pi }×d$
Here, $$d$$ is the distance which is twice the radius of the circle. So we can rewrite the formula as below.
Circumference of circle $$=$$ $\mathrm{\pi }×2r$. Here $\mathrm{\pi }=\frac{22}{7}$ or $$3.14$$