Chord (geometry)

A chord of a plane curve k is the connecting two points on k

Tendon at the county

The chord of a circle divides the circle into two usually unequal size arcs and, in each of which the peripheral angle theorem: All triangles with the tendon as base side and a third point on one of arches or have into equal angle or.

Runs the string through the center of the circle, it is called diameter. The peripheral angle is then a right angle ( theorem of Thales ).

For the chord length

And due and

Historically, the chord length was calculated using the rarely used angle function Chord. Previously, the solder of the tendon was referred to the center of the circle as Apothem. The extension of the solder on the tendon out on the edge of the circle called Sagitta. The length of apothem and Sagitta together make the circle radius.

Al- Battânîs (* btw 850 and 869, † 929 ) was the first who used the sine instead of geometric tendons.