Transcript Slide 1

Angles, Circles, and parts of Circles
secant: a line, ray, or segment that contains a chord
chord: segment has endpoints on circle
tangent: a line, ray, or segment that touches the circle in one point
Tangent: a line, ray, or segment that
only intersects the circle at one point
AB is tangent to circle at point C
Central angle: vertex is at the center of the circle
Vertex is C.
Central Angle is named
<ACB or <BCA
CENTRAL ANGLE is ALWAYS in the CENTER of the CIRCLE!
Chord: segment whose endpoints lie on the circle
AD is a chord.
Note that AC and CB are NOT chords
because C is not on the circle.
BD is a chord.
Inscribed angle: vertex on the circle and
sides contain chords of circle
Inscribed Angle is named
<ADB or <BDC.
Know the difference between Inscribed angles and Central Angles.
Arc: an unbroken part of a circle
minor arc: (use 2 letters) less than ½ the circle
major arc: (use 3 letters) more than ½ the circle
congruent arcs: arcs with same measure
Arc Addition postulate
The measure of the arc formed by 2 arcs that have exactly one point in
common is the sum of the measures of the two arcs.
AB + BC = AC
Tangent Theorem:
Segment is tangent to a circle if and only if it is
perpendicular to a radius of a circle at the point of
intersection.
Practice Problems!!!!
Name the following in the diagram
A chord
A secant
An inscribed angle
A central angle
A line tangent to the circle
A minor arc
A major arc
Click on next slide to see if your answers are correct.
Practice Problems!!!!
Name the following in the diagram
A chord DC or DA
A secant line m
An inscribed angle <ADC
A central angle <ABD or <ABC
A line tangent to the circle line h
A minor arc AD or AC
A major arc CDA or ADC