1. LINES THAT INTERSECT CIRCLES Geometry CP2 (Holt 12-1) K. Santos

2. Circle definition Circle: points in a plane that are a given distance (radius) from a given point (center). Circle P P Radius: center to a point on the circle

3. Interior & Exterior of a circle Interior of a circle: points inside the circle Exterior of a circle: points outside the circle exteriorinterior

4. Lines & Segments that intersect a circle A G O B F E C D Chord: is a segment whose endpoints lie on a circle. Diameter: -a chord that contains the center -connects two points on the circle and passes through the center Secant: line that intersects a circle at two points

5. Tangent

6. Pairs of circles Congruent Circles: two circles that have congruent radii Concentric Circles: coplanar circles with the same center

7. Tangent Circles Tangent Circles: coplanar circles that intersect at exactly one point Internally tangentexternally tangent circlescircles

8. Common Tangent Common tangent: a line that is tangent to two circles Common externalcommon internaltangents

9. Theorems 12-1-1 & 12-1-2

10. Example

11. Example—Is there a tangent line?

12. Example

13. Theorem 12-1-3

14. Example: