The diameter is the line segment that passes through the center and joins two opposite points of a circle. It is easy to calculate using a ruler or calculations if you know one of the three parameters: radius, area, or circumference.
Here we will show you two ways to find the diameter of a circle. To do this calculation, you will need a calculator.
How to find the diameter if the radius is known
The radius is the line segment that connects the circle’s center with its edge. It is half the diameter. Therefore, to calculate the diameter, simply multiply the value of the radius by 2.
How to find the diameter if the area is known
Suppose you know the area of a circle. In that case, you can calculate the diameter as follows:
- 1º Step: Multiply the area value by 4.
- 2º Step: Divide by π (approximately 3.14).
- 3º Step: Take the root of the resulting number.
Let’s say the area of our circle is 30 cm2.
So, (30 ・ 4) / 3.14 = 38.21.
Let’s use a calculator and take the root of this number. The result indicates that the diameter of the circle is 6.18 cm.
