To find the area of a sector, divide the angle of the sector by 360 degrees, then multiply the answer by pi and the square of the radius. You need to know the angle and radius of the circle. A ruler, a calculator and a protractor are helpful in this task.
- Measure the sector
Using a ruler, measure the radius of the circle, and record it. Use several strokes of the ruler if the radius is longer than the ruler. Use a protractor to measure the angle of the sector, and record this measurement. Make sure the baseline of the protractor is squarely aligned to the radius when measuring the angle. Repeat this step to verify the measurements.
- Divide the angle by 360 degrees
Using a calculator, divide the angle of the sector by 360 degrees, and record the answer.
- Calculate the area of the sector
Square the radius, and multiply the product by 22/7 to get the area of the circle. Multiply the area of the circle by your answer in step two above to get the area of the sector in question. For instance, if the answer in step two above is 1/4, and the area of the circle is 320 square centimeters, then the area of the sector in question is 80 square centimeters.