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Angles Interior to circles. A segment or arc is said to subtend an angle if the endpoints of the segments or arc lie on the sides of the angle. Inscribed angles are one type of subtended angle . < BAC is subtended by arc BC or segment BC.
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Angles Interior to circles A segment or arc is said to subtend an angle if the endpoints of the segments or arc lie on the sides of the angle. Inscribed angles are one type of subtended angle. < BAC is subtended by arc BC or segment BC
Another type of subtended angle is one formed by a tangent to the circle and a chord of the circle
Theorem 64-1 • The measure of an angle formed by a tangent and a chord is equal to half the measure of the arc that subtends it. • m<ACD = 1/2 m arc AC 140o D
Finding angle measures with tangents and chords • Find a<ABC Find arc BC A B 76o B C 30o A C
Theorem 64-2 • The measure of an angle formed by 2 chords intersecting in a circle is equal to half the sum of the intersected arcs. • m<1 = 1/2 (m arc EF +m arc GH) • m<2= 1/2 (m arc EG and m arc FH) G E 1 2 H F
Find x 45o 59o x