It is demonstrated by Euclid, that all the Angles in the same Segment are equal to one another; that is, any Angle EHG is equal to any Angle EFG in the same Segment EFG.
The Angle at the Periphery, or in the Segment, is comprehended between two Chords AB and BD, and stands on the Arch AB. See CHORD, &c.
The Measure of an Angle without the Periphery G, (fig. 96.) is the Difference between half the Concave Arch LM, whereon it stands, and half the Convex Arch NO, intercepted between its Legs.