6.3 – 6.4 Properties of Chords and Inscribed
Angles
Theorem Review: ◦Two tangents from the same point are
congruent◦Tangents are perpendicular (form a 90 degree
angle) with the radius◦A central angle has the same measure as its
arc Minor Arcs contain 2 letters and are < 180 degrees Major Arcs contain 3 letters and are > 180 degrees Semicircles = 180 degrees
.
Chord Properties: ◦If two arcs are congruent then the
corresponding chords are congruent
Chord Properties continued…◦If one chord is a perpendicular bisector of
another chord, then the first chord is the diameter
◦If a diameter is perpendicular to a chord, then the diameter bisects the chord and its arc.
◦See “cat” drawing
ANGLE = ½ ARCIf Arc AB = 80o
Then m<C=40o
Inscribed Angles◦An inscribed angle is an angle whose vertex is
ON THE CIRCLE This is different from a central angle whose vertex
is ON THE CENTER OF THE CIRCLE
Practice page 207 16-18
Quadrilateral inside a Circle◦If a quadrilateral is inside of a circle, then the
opposite angles sum to 180 (they are supplementary).
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