AO and OB are called radius

AC, BC and AB are called strings

Angle ACB is a circular Angle

Angle AOB is the central image

Bending AB part is arc arc.

OE is the edge distance

trigonometric AOB is trigonometric district

ED is the arch height

Arc length Calculator formulas is: (Central Angle / 180°) •π • r

The yellow area is sector

sector area formulas is: (Angle AOB / 360°) •π • r²

Green area is the arch height area

This area magnitude = sector area - AOB trigonometric