How to find the area of a circle and its parts

Calculating area of a circle and its parts refers to the geometry problems 9th grade. The ability to solve them you may need not only to help your child with geometry, but also to perform technical tasks at work or at home. Applying the formula to calculate the area of a circle can, for example, to calculate the consumption of materials according to drawings in the construction of a circular pool or calculate the cross-sectional area of the electrical cable when performing electrical work.

You will need

• To find the area of a circle:
• - geometric formula for finding the area of a circle S = Пхг2, where:
• - S - the area of a circle;
• - P - the number "PI", it is constant and equal to the value of 3.14;
• - r is the radius of the circle.
• To find the area of sector of a circle:
• geometric formula S=P x r2 / 360° x n°, where:
• - S - the area of a sector of a circle;
• - P - the number "PI", it is constant and equal to the value of 3.14;
• - r - the radius of the circle;
• - n - value Central angle of the sector in degrees.

Instruction

1. Measure the radius of the circle with a ruler. Calculate the value of the area of a circle by the geometric formula for finding the area of a circle (area of a circle equals the product of PI and the square of the radius of the circle).
2. Erect for finding the area of a circle the length of the radius of the circle in the square, multiply the resulting number by the number "PI" (its value is constant and equal to 3.14). So, using the formula you find the area of a circle.
3. Measure the sector angle in degrees with a protractor. The area of a circle you already know. Calculate the value of area of sector of a circle the formula for the geometric (area of sector of a circle equals the area of a circle with radius r on the ratio of sector angle n° to the angle in a full circle, i.e. 360°).
4. Divide the value of the area of a circle by 360 and multiply by the size of the sector angle in degrees. So you will find the amount of area of sector of circle degree measure of its angle.