Area of a Semicircle

Semicircle Area Formula

The formula for area of a semicircle is given as:
A = 12πr2
Where A is the area and r is the radius.

area of a semicircle

Example Problems

Problem 1:
What is the area of a semicircle with a radius of 5?
1.) Let’s plug the radius into the area formula.
A = 12πr2
A = 12π(52) = 12.5π
2.) The area is 12.5π.

Problem 2:
A semicircle’s area is measured to be 4.5π square meters. What is the radius in meters?
1.) Let’s plug the area into the formula.
A = 12πr2
4.5π = 12πr2
2.) Now we will solve for the radius r.
4.5 = 12r2
r2 = 9
r = 3
3.) The radius is 3 meters.

Result :

Worksheet 1


Cheat sheet


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