# Diameter & Radius of Circle

When you are having a biscuit or a cookie have you wondered if it is the circle in shape? The clock hanging on your wall, the cap of a bottle, the bangles worn by your mom, the ring that is worn by your lover these are all in the shape of a circle. A circle is a two-dimensional shape that can be defined as a collection of points on its surface & all the points being at an equal distance from the center of the circle.

Now you might think what does the radius and the diameter of circle mean. The radius which is denoted by the letter ‘r’ is defined as the distance from the midpoint also known as the center of the circle to any random point on its surface. The diameter denoted by the letter ‘d’ is generally twice the length of the radius. It is known to be the longest chord of a circle. We can also represent the diameter of a circle as ‘dia’ or ‘D’.

In this article, we will solve a few examples which will help us understand the concept of the radius as well as the diameter of any given circle.

Contents

We already have an idea of what the radius of circle is. The radius of a circle holds a very essential place in all circle-related formulas. Therefore, we can say that radius is known to be an important part of a circle.

There are two formulas you need to keep in mind while doing any kind of calculations involving a circle,

In any question, if the diameter of the circle has been given you can use this formula to calculate the radius. Radius Formula = diameter of the circle/2

In any question, if the radius of the circle has been given you can use this formula to calculate the diameter. The diameter of a circle equals twice the radius.

## Formula to Calculate the Radius & Diameter of Circle

A circle’s or sphere’s radius is computed using precise calculations. Here we are studying the radius of a circle formula; please see the section below for further information:

The formula for radius can be derived from the diameter, let’s see how we can do that: – This is defined as the straight line running through the center of the circle, connecting a single point by one end to the other end of the circle.

In this situation, the diameter is therefore double the size of the radius. This may be expressed mathematically as – 2 radius. This is also referred to as the circle’s longest chord.

## Solved Examples

Example 1: Rahul needs to make a circular table. The radius of the given table is equal to 20 cm. What will be the diameter of the table?

Solution: Let’s note down the information given in the question above,

We have already discussed the formula to calculate the Diameter of any given circle = 2R

Therefore, the Diameter of the circular table will be equal to 2*20 = 40 cm.

Example 2:  Sam makes a circle. The diameter of the circle is equal to 10 cm. Find the radius of the circle constructed by Sam.

Solution: Let’s note down the information given in the question above,

Diameter= 10 cm

We have already discussed the formula to calculate the Radius of any given circle is to divide the given diameter by 2.

Therefore, the radius of the circle will be equal to 10/2 = 5 cm

The concepts of this chapter if learned online can be grasped very easily. Maths online classes for topics like diameter & radius of a circle, help students visualize problems and the solutions attached to them in a fun way. If you are interested in taking online maths classes, visit Cuemath.