Section 9-3 Arcs and central angles

Central angle §An angle with its vertex at the center of the circle.

Arcs of circle A §An unbroken part of a circle. §Minor arc BC contains the interior points of § Major arc BDA contain the remaining points §Endpoints of a diameter create a semicircle

Arcs of Circle A cont..

What do you notice?

Minor arcs §The measure of a minor arc is defined to be the measure of its central angle

What relationship do you notice?

Arc addition postulate §The measure of the arc formed by 2 adjacent arcs is the sum of the measures of these 2 arcs.

Congruent arcs §2 arcs in the same circle or congruent circles that have the same measure are congruent

Congruent arc theorem §In the same circle, or congruent circles, two minor arcs are congruent if and only if their central angles are congruent