1. Bisectors of Triangles LESSON 5–1

2. Over Chapter 4 5-Minute Check 1 A.scalene B.isosceles C.equilateral Classify the triangle.

3. Over Chapter 4 5-Minute Check 2 A.3.75 B.6 C.12 D.16.5 Find x if m  A = 10x + 15, m  B = 8x – 18, and m  C = 12x + 3.

4. Over Chapter 4 5-Minute Check 5 A.22 B.10.75 C.7 D.4.5 Find y if ΔDEF is an equilateral triangle and m  F = 8y + 4.

5. Over Chapter 4 5-Minute Check 6 A.(–3, –6) B.(4, 0) C.(–2, 11) D.(4, –3) ΔABC has vertices A(–5, 3) and B(4, 6). What are the coordinates for point C if ΔABC is an isosceles triangle with vertex angle  A?

6. Then/Now You used segment and angle bisectors. Identify and use perpendicular bisectors in triangles. Identify and use angle bisectors in triangles.

7. Concept

8. Example 1 Use the Perpendicular Bisector Theorems A. Find BC.

9. Example 1 Use the Perpendicular Bisector Theorems B. Find XY.

10. Example 1 Use the Perpendicular Bisector Theorems C. Find PQ.

11. Concept

13. Example 3 Use the Angle Bisector Theorems A. Find DB.

14. Example 3 Use the Angle Bisector Theorems B. Find m  WYZ.

15. Example 3 Use the Angle Bisector Theorems C. Find QS.

16. Concept

17. Example 4 Use the Incenter Theorem A. Find ST if S is the incenter of ΔMNP.

18. Example 4 Use the Incenter Theorem B. Find m  SPU if S is the incenter of ΔMNP.

19. Example 4 A.12 B.144 C.8 D.65 A. Find the measure of GF if D is the incenter of ΔACF.

20. Example 4 A.58° B.116° C.52° D.26° B. Find the measure of  BCD if D is the incenter of ΔACF.