Around call a flat geometrical figure, and the line limiting it, it is accepted to call a circle. The main property of a circle is that each point on this line is at identical distance from the center of a figure. The piece from the beginning in the center of a circle and the termination on any of points of a circle is called radius, and the piece which is connecting two points of a circle and passing through the center - diameter.
Instruction
1. Find diameter circle length doubling of length of its radius if this length is known. It is simplest option of basic data to determine diameter length if necessary.
2. Use Pi's number for finding of length of diameter on the known length of a circle. This constant expresses a constant ratio between these two parameters of a circle - irrespective of the circle sizes, division of length of its circle into diameter length always gives the same number. From this follows that for finding of length of diameter it is necessary to divide length of a circle into Pi's number. As a rule, for practical calculations of length of diameter there is enough accuracy to the 100-th shares of unit, that is to two signs after a comma therefore Pi's number can be considered equal 3.14. But as this constant is number irrational, has infinite number of signs after a comma. If there is a need for more exact determination of diameter of a circle, then the necessary number of signs for number p it is possible to find, for example, according to this reference - http://www.math.com/tables/constants/pi.htm.
3. At the known area of a circle (S) for finding of length of diameter (d) double a square root from the area relation to Pi's number: d=2 ∗√ (S/π).
4. With the known length of the party of the rectangle spun near, length of diameter will be equal to this known size.
5. With the known lengths of the parties (an and b) the rectangle entered in a circle, length of diameter (d) it is possible to calculate, having found length of diagonal of this rectangle. As diagonal is a hypotenuse here in a rectangular triangle which legs form the parties of the known length, on Pythagorean theorem diagonal length, and together with it and length of diameter of a circumscribed circle, can be calculated, having found a square root from the sum of squares of lengths of the known parties: d= √ (a² + b²).