Circle — the closed curve which all points are from one point equally spaced. This point - the center of a circle, and a piece between a point on a curve and its center is called circle radius.
Instruction
1. If through the center of a circle to draw a straight line, then its piece between two points of intersection of this straight line with a circle is called diameter of this circle. A half of diameter, from the center to diameter point of intersection about a circle are radiusokruzhnost. If to cut a circle in any point, to straighten and measure, then the received size is length of this circle.
2. Draw several circles different solution of compasses. Visual comparison allows to draw a conclusion that large diameter outlines the bigger circle limited to a circle with a bigger length. Therefore, between diameter of a circle and its length there is directly proportional dependence.
3. On physical sense the "circle length" parameter corresponds to perimeter of the polygon limited to the broken line. If to enter in a circle the correct n-square with the party of b, then the perimeter of such figure P is equal to the work of the party of b on number of the parties of n: É =. The party of b can be determined by a formula: b=2R*Sin (π/n) where R is the radius of a circle in which entered the n-square.
4. At increase in number of the parties the perimeter of the entered polygon will approach more and more length of a circle of L. É = b*n=2n*R*Sin (π/n) =n*D*Sin (π/n). The dependence between length of a circle of L and with an its diameter of D is constant. L/D=n*Sin relation (π/n) at aspiration of number of the parties of the entered polygon to infinity aspires to number π, the constant called "number p" and expressed by a recurring decimal decimal. For calculations without application of computer facilities the value π=3.14 is accepted. Length of a circle and its diameter are connected by a formula: L = πD. For calculation of diameter of a circle divide its length into number π=3.14.