The notion of a chord in the school course of geometry is associated with the notion of a circle. Circumference is a plane figure composed of all points of this plane that are equidistant from a given plane.
The radius of a circle is the distance from the center to any point lying on it. A walk is a segment joining any two points lying on a circle.
The longest chord passes through the center of the circle, while it is called the diameter, and is denoted by d. The length of such a chord is
D = 2 * R, where R is the radius of the circle.
To obtain the length of an arbitrary chord it is necessary to introduce an additional concept.
The angle with the vertex in the center of the circle is called the central angle of this circle.
If the degree measure of the central angle is known, then the chord length on which it rests is calculated by formulas
H = 2 * R * sin (?? / 2)
H = R * v (2 * (1 - cos ??))
H = 2 * R * cos ??, where ?? = (Π -?) / 2, Π is the number Π