Method #1 – Circumference from the Radius
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Formula – How to calculate the circumference of a semicircle from the radius
π is approximately equal to 3.1415926535
Circumference = (π x Radius) + (2 x Radius)
Example
A semicircle has a radius of 10
Circumference = (π x 10) + (2 x 10) = (3.14159 x 10) + (2 x 10) = 314.159 + 20 = 334.159
Method #2 – Circumference from the Diameter
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Formula – How to calculate the circumference of a semicircle from the diameter
π is approximately equal to 3.1415926535
Circumference = (π x Diameter ÷ 2) + Diameter
Example
A semicircle has a diameter of 20
Circumference = (π x 20 ÷ 2) + 20
Circumference = (3.14159 x 10) + 20
Circumference = 314.159 + 20
Circumference = 334.159
Method #3 – Circumference from the Area
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Formula – How to calculate the circumference of a semicircle from the area
π is approximately equal to 3.1415926535
Step 1: Find the radius from the area
Radius = √(2 x Area ÷ π)
Step 2: Find the circumference from the radius
Circumference = (π x Radius) + (2 x Radius)
Example
A semicircle has an area of 300
Radius = √(2 x 300 x π)
Radius = √(2 x 300 x 3.14159)
Radius = √1884.954
Radius = 43.416
Circumference = (π x 43.416) + (2 x 43.416)
Circumference = (3.14159 x 43.416) + (2 x 43.416)
Circumference = 136.395 + 86.832
Circumference = 223.227