Instruction
1
Most often the tasks required to calculate the length of circumference (L) by the known radius of the circle (R). These two parameters are linked through perhaps the most well-known among the population of our planet is a mathematical constant - PI. She has appeared in mathematics as an expression of a constant ratio between the length of the circumference and diameter, that is, twice the radius. Therefore, to solve the problem multiply the radius by two PI: L = R*2*π.
2
Since the area of the circle (S) can be expressed using its radius, the formula from the previous step can be transformed to calculate the perimeter of the circle (L) at the famous square. The radius is the square root of the ratio between the area and the number PI - the substitute this expression into the formula from the previous step. You should get this formula: L = √(S/π)*2*π. It can be slightly simplified: L = 2*√(S*π).
3
The length of the circumference as a whole can be calculated and knowing the length of some parts of (l) together with the value mapped to this arc Central angle (α). The ratio of two initial quantities equal to the radius of the circle if the angle is expressed in radians. Substitute this expression for the radius into the formula from step one and you will get this equality: L = l/α*2*π.
4
If the original terms of the side length of a square (A) inscribed in a circle, one of this values is sufficient for finding the perimeter of a circle. The radius in this case will be equal to the product of the length of the sides of the quadrilateral to the square root of two. Substitute this expression in the same formula from the first step to obtain this equality: L = A*√2*2*π.
5
Knowing the same amount - the length of a side (A) of the square described about the circle, it is possible to obtain an even more simple formula for calculating the perimeter of a circle (L). As in this case, the length of a side is the same as the diameter, calculate the following formula: L = A*π.