Question

Prove the formula of circle. Its area and circumference.​

Answer 1

Circumference of circle is 2pier where r is radius and pie is 22/7 or 3.14 and the area of circle is pier^2 hope this helps you

Answer 2

This page describes how to derive the formula for the circumference of a circle.

Recall that the definition of pi (π) is the circumference c of any circle divided by its diameter d. Put as an equation, pi is defined as

π = cd

Rearranging this to solve for c we get

c = πd

The diameter of a circle is twice its radius, so substituting 2r for d

c = 2πr



Consider a circle divided into large number of sectors as shown 


Cut the sectors and arrange them as shown so that it forms a rectangle 

Length of rectangle = half the circumference of the circle = 2Пr/2= Пr Breadth of the rectangle = r (radius of the circle) Area of rectangle = length x breadth =  πr  x r =  πr2 Hence area of a circle is πr2 sq units.