How Do You Find the Area of a Semicircle?

By Staff WriterLast Updated Apr 4, 2020 11:45:10 PM ET

To find the area of a semicircle, use the formula 1/2(pi x r^2). You need the value of "r," or radius of the circle, and pi.

  1. Determine the radius

    Measure the distance from the center of the circle of which the semicircle is part to its edge. This is its radius.

  2. Find r2

    Multiply the radius of the semicircle by itself.

  3. Multiply pi by r^2

    Find the product of pi, which is rounded to 3.14, and the square of the radius.

  4. Determine the area

    Using the formula for finding the area of a semicircle, divide the product of the squared radius and pi by 2. If the radius of the semicircle is 2 centimeters, then the area is 1/2(3.14 x 2 x 2), or 6.28 square centimeters.