The perpendicular distance from an arc's midpoint to the chord across it, equal to the radius minus the apothem ,
(1)
|
For a regular polygon of side length ,
(2)
| |||
(3)
| |||
(4)
| |||
(5)
| |||
(6)
|
where is the circumradius, the inradius, is the side length, and is the number of sides.