1. Standard
Understand and use properties of chords, tangents, and secants as an application of triangle similarity.
b. Understand and use properties of central, inscribed, and related angles.

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

3. Parts of a Circle
Circle F F F
center
Use the center to name a circle.

4. CHORD: a segment whose ________ are on the circle
endpoints

5. RADIUS: distance from the _____ to a point on the circle
center P

6. DIAMETER: distance ______ the circle through its ______
across P
center
Also known as the longest chord.

7. What is the relationship between the diameter and the radius of a circle?OR
D =
½ D
2 r

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

10. SECANT sounds like second
Secant Line
A secant line intersects the circle at exactly TWO points.
SECANT sounds like second

11. TANGENT: a LINE that intersects the circle exactly ONE time

12. Point of Tangency

13. Parts of a Circle chord tangent secant diameter radius
Segments & Lines

14. Two circles can intersect…
in two points
one point
or no points

15. No points of intersection (different center)

16. No points of intersection (same center)
Concentric Circles
Same center but different radii

17. 1 point of intersection (Tangent Circles)
Externally Tangent
Internally Tangent

18. 2 points of intersection

19. Common Tangents
Internal

20. Common Tangents
External

21. Types of Angles Central angle Inscribed angle
- Vertex is on the center.
Inscribed angle
- Vertex is on the circle.

22. Arcs: An ARC is an unbroken part of a circle
If the central angle that forms the arc is less than 180°, it is a MINOR ARC
The points on the circle that do not form the minor arc form a MAJOR ARC
The arc that lies in the interior of an inscribed angle and has endpoints on the angle is called the INTERCEPTED arc.

23. Types of Arcs
major arc
minor arc
semicircle M
MNO P MO O N
MON

24. Measure of Arcs & Angles
minor arc = its central angle
major arc = its central angle
68°
360 – 68 = 292
68°
292°

25. Measure of Arcs & Angles
minor arc = its central angle
major arc = its central angle
semicircle = 180
180°

26. Secant Radius Diameter Chord Tangent
Name the term that best describes the line.
Secant
Radius
Diameter
Chord
Tangent