Sagitta
A sagitta (pronounced sah-JIT-uh) is the height of an arc above its chord: the straight line joining the arc's two endpoints. It is useful when laying out curves from a known circle radius. It is very useful for knowing how to calculate the size of something like contact lenses for your eyes.
Sagitta Formula
Solve for Radius
The sagitta formula can be used to solve for the radius of a circle given the sagitta and chord length, which is incredibly useful in something like CAD work.
Resources
Which Editor (2026)