Pg 603

 An angle whose vertex is the center of the circle

 Minor Arc  CB  Major Arc  BDC  Semicircle  Endpoints of the arc are a diameter

 Minor Arc  The measure of the central angle  Major Arc  360 – minor arc  Congruent Arcs  Have the same measure

 MN  80 °  MPN  360 – 80 = 280 °  PMN  180 °

 The measure of an arc formed by two adjacent arcs is the sum of the measures of the two arcs.  mABC = mAB +mBC

 GE  = 120 °  GEF  = 230 °  GF  360 – 230 = 130 °

 In the same circle, or in congruent circles, two minor arcs are congruent if and only if their corresponding chords are congruent.  if and only if

 If a diameter of a circle is perpendicular to a chord, then the diameter bisects the chord and its arc. 

 If one chord is a perpendicular bisector of another chord, then the first chord is a diameter.

 In the same circle, or in congruent circles, two chords are congruent if and only if they are equidistant from the center.

 CD = 10