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A day full of math games & activities. Find one near you.

# 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 = Circumference/π and r = d/2 we can find the 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)

⇒ r = d/2 = C/2π

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)

### Hence, using the formula d = C/π and r = d/2 we can find the diameter and radius of a circle

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