The circle is the simple geometrical figure which does not have corners. If to measure distance from the center of a circle to any its extreme point, it will be always equal to radius. In tasks, as a rule, it is required to calculate diameter or to find the area of a circle. It is easy to calculate these indicators if the radius of a circle is known.
It is required to you
- - calculator.
Instruction
1. For determination of the area of a circle at first square its radius, that is in the second degree. And then result increase by number π (p). If in a task instead of radius diameter of a figure is given, you can divide it into 2 previously. Now use the radius of a figure received at division for convenience of calculation of the area of a circle.
2. For finding of value of a square of radius of a circle use the calculator. For a start enter circle radius size, and then find the special button with designation h2. This symbol on the button shows that the number will be built in the second degree. If you had difficulties, increase circle radius by yourself. To find the area of a circle, you can use also diameter. Radius is ½ from diameter, so it can be presented in the fraction form where in numerator there will be diameter size, and in a denominator - 2. At calculation of a square of such fraction on the calculator build value of diameter of a circle in the second degree, and then divide the received number into 4.
3. Increase value of a square of radius of a circle by coefficient π (p). To find the area of a circle, you can use more exact or rounded its value. For this purpose gather the corresponding number (3.1415926535897932384626433832795 or 3.14). Often there is an opportunity to use the special button designated by a symbol π (p), provided on many models of calculators.
4. Measure the area of a circle in square sizes. If radius was given in centimeters (cm), then the area will be expressed in square centimeters (cm2). At calculation of radius from diameter of a circle the unit of measure does not change. For example, if diameter was given in inches, then and radius will be measured in inches, and the required area will be received in inches square. In a statement of the problem not always radius is specified at once. Diameter of a circle is sometimes initially given. If not to notice it and to use diameter for calculations instead of radius, then mistakes in calculations are inevitable. To find radius, divide the size of diameter into 2.