11.1.2 Arcs and Chords Flashcards
central angle
an angle whose vertex is the center of a circle
arc
an unbroken part of a circle consisting of two points called the endpoints and all the points on the circle between them
minor arc
an arc whose points are on or in the interior of a central angle
major arc
an arc whose points are on or in the exterior of a central angle
endpoints of an arc
lie on a diameter, the arc is a semicircle
adjacent arcs
the arcs of the same circle that intersect at exactly one point
congruent arcs
within a circle or congruent circles, they are two arcs that have the same measure
Arc Addition Postulate
The measure of an arc formed by two adjacent arcs is the sum of the measure of the two arcs.
Theorem In a circle or congruent circles
(1) Congruent central angles have congruent chords.
(2) Congruent chords have congruent arcs.
(3) Congruent arcs have congruent central angles.
Theorem In a circle
if a radius (or diameter) is perpendicular to a chord, then it bisects the chord and its arc.
Theorem In a circle
the perpendicular bisector of a chord is a radius (or diameter)