1. AGENDA Notes on Circles Notes on Central Angles Practice Worksheet
Homework Worksheet

2. Unit 3
Circles

3. Segments
of Circles

4. Parts of a Circle
Circle – set of all points _________ from a given point called the _____ of the circle.
equidistant C
center
Symbol: C

5. CHORD:
A segment whose endpoints are on the circle

6. Radius
RADIUS:
Segment from the center to point on circle P

7. A Chord that passes through the center.
Diameter
DIAMETER:
A Chord that passes through the center. P
Also known as the longest chord.

8. D = ? 24 32 12
r = ? 16
r = ?
4.5 6
D = ? 12 9

9. Use P to determine whether each statement is true or false.Q R T S
True: thumbs up False: thumbs down

10. Secant:
A line that intersects the circle at exactly TWO points

11. 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

12. Secant Radius Diameter Chord Tangent
Name the term that best describes the notation.
Secant
Radius
Diameter
Chord
Tangent

13. Concentric Circles

14. Common Tangents
Go To Page 8

15. Central
Section 6.2
Arcs

16. <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

17. Semicircle: An Arc that equals 180°
To name: use 3 letters E D
EDF P F

18. THINGS TO KNOW AND REMEMBER ALWAYS p. 7
A circle has ___ degrees
A semicircle has ___ degrees
Vertical Angles are ______
Linear Pairs are __________

19. measure of an arc = measure of central angle
96 Q
m AB =
96° B C
m ACB =
264°
m AE =
84°

20. Arc Addition PostulateB
m ABC =
+ m BC
m AB

21. 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

22. 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”

23. Classwork
P. 8 Worksheet

24. Homework:
Practice Worksheet