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Radius of a Semicircle Calculator

LAST UPDATE: November 7th, 2024

Method #1 – Radius from the Area

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Formula – How to calculate the radius of a semicircle from the area

π is approximately equal to 3.1415926535

Radius = √(2 x Area ÷ π)

Example

A semicircle has an area of 300

Radius = √(2 x 300 ÷ π)

Radius = √(2 x 300 ÷ 3.14159)

Radius = √190.986

Radius = 13.8198

Method #2 – Radius from the Circumference

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Formula – How to calculate the radius of a semicircle from the circumference

π is approximately equal to 3.1415926535

Radius = Circumference ÷ π

Example

A semicircle has a circumference of 35

Radius = 35 ÷ π = 35 ÷ 3.14159 = 11.14086

Method #3 – Radius from the Diameter

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Formula – How to calculate the radius of a semicircle from the diameter

Radius = Diameter ÷ 2

Example

A semicircle has a diameter of 20

Radius = 20 ÷ 2 = 10