1. Lines that Intersect Circles
12.1

2. The interior of a circle is the set of all points inside the circle
The interior of a circle is the set of all points inside the circle. The exterior of a circle is the set of all points outside the circle.
exterior
interior

4. Example 1: Identifying Lines and Segments That Intersect Circles
Identify each line or segment that intersects L.
chords:
secant:
tangent:
diameter:
radii:
JM and KM JM m KM
LK, LJ, and LM

5. Identify each line or segment that intersects P.
Check It Out! Example 1
Identify each line or segment that intersects P.
chords:
secant:
tangent:
diameter:
radii:
QR and ST ST UV ST
PQ, PT, and PS

6. Pairs Of Circles….Congruent Circles
Have congruent radii

7. Pairs of Circles…Concentric Circles
Coplanar circles
With same
center

8. Pairs of Circles….Tangent Circles
Internally Tangent
Externally Tangent
Intersect in one point

9. Example 2: Identifying Tangents of Circles
Find the length of each radius. Identify the point of tangency and write the equation of the tangent line at this point.
radius of R: 2
radius of S: 1.5
point of tangency: (–2, 0)
equation of tangent line: y = 0

10. Check It Out! Example 2
Find the length of each radius. Identify the point of tangency and write the equation of the tangent line at this point.
radius of C: 1
radius of D: 3
Pt. of tangency: (2, –1)
eqn. of tangent line: y = –1

11. A common tangent is a line that is tangent to two circles.

12. A common tangent is a line that is tangent to two circles.

16. HK and HG are tangent to F. Find HG.

17. RS and RT are tangent to Q. Find RS.

18. HK and HG are tangent to F. Find HG.

19. Assignment
Pg (11-14, 16-27, 31-33)