Arcs
A minor arc is the shorter arc connecting two endpoints on a circle.
The measure of a minor arc is less than 180°, and equal to the measure of the arc's central angle.
A major arc is the longer arc connecting two endpoints on a circle.
The measure of a major arc is greater than 180°, and equal to 360° minus the measure of the minor arc with the same endpoints.
An arc measuring exactly 180° is called a semicircle.
In the figure, 
and 
.
Note that the minor arc is named with just the two endpoints, while the major arc is named with three letters, the two endpoints and a third point on the arc.
