How to find the diameter of a circle

The circle is called a geometric figure in the plane consisting of all points in this plane are equidistant from a given point. Given the point is called the center of the circle, and the distance at which points of a circle are its center, radius of the circle. The region of the plane bounded by a circle called the circle.There are several methods of calculating the diameter of a circle, the choice of the specific depends on the available original data.

Instruction

1. In the simplest case, if you construct a circle of radius R, then its diameter will be equal to
   D = 2 * R
   If the radius of the circle is not known, but is known for its length, the diameter can be calculated according to the formula of length of circumference
   D = L/N where L is the length of the circumference, N is the number of P.
   The diameter of the circle can be calculated by knowing the area of a circle it limited
   D = 2 * v(S/P), where S is the area of a circle, N is the number of P.
   
2. In special cases the radius of the circle can be found if it is described or inscribed in a triangle.
   If the circle inscribed in a triangle, then its radius is given by
   R = S/p where S is the area of a triangle, p = (a + b + c)/2 – properiter triangle.
   
3. For the circledescribed about a triangle, the formula for the radius has the form
   R = (a * b * c)/4 * S, where S is the area of a triangle.