10-3: Arcs & Chords Geometry March 29, 2010
Inscribed & Circumscribed Quad WXYZ is an inscribed polygon because all of its vertices lie on the circle. Circle A is circumscribed about the polygon because it contains all the vertices of the polygon. W X Y Z A
Ex 1: A circle is circumscribed about a regular pentagon. What is the measure of the arc between each pair of consecutive vertices?
Theorem 10.3 If a diameter (or radius) is perpendicular to a chord, then it bisects the chord and its arc. If BA TV, then UT UV and AT AV. If a diameter (or radius) is perpendicular to a chord, then it bisects the chord and its arc. If BA TV, then UT UV and AT AV. B C U A TV
Ex 2: Circle W has a radius of 10 cm. Radius WL is to chord HK which is 16 cm long. a)If HL = 53 , find MK. b)Find JL.
Theorem 10.4 In a circle or in 2 circles, two chords are congruent if and only if they are equidistant from the center.
Ex 3: Chords EF & GH are equidistant from the center. If the radius of circle P is 15 and EF = 24, find PR and RH. EQ F P G R H