1. Chapter 6 Circles

2. 10.1 Exploring Circles

3. 3 Circle Vocabulary Circle – set of all points equidistant from a point Chord – segment whose endpoints are on the circle Interior Point – A Exterior Point – B Diameter – Chord that passes through the center Radius – segment whose endpoints are the center and a point on the circle B A

4. 4 Circle Vocab. Cont. Tangent – Line which intersects the circle at exactly one point Point of Tangency – the point where the tangent line and the circle intersect (C) Secant – Line which intersects the circle at exactly two points C

5. 5 Circle Vocab. cont. Common Tangents – A line which is tangent to two circles Common Internal Tangents Common External Tangents

6. 10.2 Properties of Tangents

7. 7 Radii and Tangents If a line is tangent to a circle, then it is perpendicular to the radius at the point of tangency. If a line is perpendicular to a radius of a circle then the line is tangent to the circle.

8. 8 Application An ice skater is racing on a circular track. The skater falls and stops after 20 meters. The track has a radius of 25 meters. How far from the center of the track is the skater? 20 25 ?? 20 2 + 25 2 = c 2 1025 = c 2 c = 32.02 meters

9. 9 If two segments from the same exterior point are tangent to a circle, then they are congruent. A B T

10. 10 Inscribed and Circumscribed Inscribed – Inside Circumscribed – Outside