Semicircle Area Formula

The formula for area of a semicircle is given as:

A = ¹⁄₂πr²

Where A is the area and r is the radius.

Area of a Semicircle Example Problems

Let's go through a couple of example problems together to practice finding the area of a semicircle.

Example Problem 1

What is the area of a semicircle with a radius of 5?

Solution:

1. Let's plug the radius into the area formula.
2. A = ¹⁄₂πr²
3. A = ¹⁄₂π(5²) = 12.5π
4. The area is 12.5π.

Example Problem 2

A semicircle's area is measured to be 4.5π square meters. What is the radius in meters?

Solution:

1. Let's plug the area into the formula.
2. A = ¹⁄₂πr²
3. 4.5π = ¹⁄₂πr²
4. Now we will solve for the radius r.
5. 4.5 = ¹⁄₂r²
6. r² = 9
7. r = 3
8. The radius is 3 meters.