# The radius and diameter of a circle

## Question: How to find the radius and diameter of a circle?

Diameter is the longest chord of the circle and radius is half of the diameter.

## Answer: Using the formula d = C/π and d = 2r we can find diameter and radius of a circle

Let's compute the diameter and radius of the circle

## Explanation:

Circumference of a circle (C) = 2πr or πd

where, r = radius of the circle, d = diameter of the circle and d = 2r

=> d = C/π ----------------------------- (1)

Let's take an example to understand this

If the circumference of a circle is 20π units then,

Diameter(d) = 20π / π = 20 units (from equation (1))

Radius = d/2= 20/2= 10 units (since, d = 2r)