AGENDA Notes on Circles Notes on Central Angles Practice Worksheet Homework Worksheet
Unit 3 Circles
Segments of Circles
Parts of a Circle Circle – set of all points _________ from a given point called the _____ of the circle. equidistant C center Symbol: C
CHORD: A segment whose endpoints are on the circle
Radius RADIUS: Segment from the center to point on circle P
A Chord that passes through the center. Diameter DIAMETER: A Chord that passes through the center. P Also known as the longest chord.
D = ? 24 32 12 r = ? 16 r = ? 4.5 6 D = ? 12 9
Use P to determine whether each statement is true or false. Q R T S True: thumbs up False: thumbs down
Secant: A line that intersects the circle at exactly TWO points
a LINE that intersects the circle exactly ONE time Tangent Line: a LINE that intersects the circle exactly ONE time Forms a 90°angle with a radius Point of Tangency: The point where the tangent intersects the circle
Secant Radius Diameter Chord Tangent Name the term that best describes the notation. Secant Radius Diameter Chord Tangent
Concentric Circles
Common Tangents Go To Page 8
Central Section 6.2 Arcs
<APB is a Central Angle Central Angle : An Angle whose vertex is at the center of the circle A Major Arc Minor Arc More than 180° Less than 180° ACB P AB To name: use 3 letters C To name: use 2 letters B <APB is a Central Angle
Semicircle: An Arc that equals 180° To name: use 3 letters E D EDF P F
THINGS TO KNOW AND REMEMBER ALWAYS p. 7 A circle has ___ degrees A semicircle has ___ degrees Vertical Angles are ______ Linear Pairs are __________
measure of an arc = measure of central angle 96 Q m AB = 96° B C m ACB = 264° m AE = 84°
Arc Addition Postulate B m ABC = + m BC m AB
240 260 m DAB = m BCA = Tell me the measure of the following arcs. D 140 260 m BCA = R 40 100 80 C B
CONGRUENT ARCS Congruent Arcs have the same measure and MUST come from the same circle or of congruent circles. C B D 45 45 110 A Arc length is proportional to “r”
Classwork P. 8 Worksheet
Homework: Practice Worksheet