Anglesof Chords,Secants,and Tangents
LearningObjective
- find the measuresof anglesformedby chords,secants,and tangents
Measureof Tangent-ChordAngle
TheoremThe measureof an angleformedby a chordand a tangentthat intersecton the circleequals
half the measureof the interceptedarc.
andIn otherwords:Proof
Drawthe radii of the circleto points and.is isosceles,therefore=
We also knowthat, because is tangentto the circle.