1. Lesson 4-6 Isosceles Triangles

2. Ohio Content Standards:

3. Describe and apply the properties of similar and congruent figures; and justify conjectures involving similarity and congruence.

4. Ohio Content Standards: Make and test conjectures about characteristics and properties (e.g., sides, angles, symmetry) of two- dimensional figures and three- dimensional objects.

5. Ohio Content Standards: Establish the validity of conjectures about geometric objects, their properties and relationships by counter-example, inductive and deductive reasoning, and critiquing arguments made by others.

6. Ohio Content Standards: Make, test and establish the validity of conjectures about geometric properties and relationships using counterexample, inductive and deductive reasoning, and paragraph or two-column proof.

7. Vertex Angle

8. Angle formed by the congruent sides in an isosceles triangle.

9. Vertex Angle Angle formed by the congruent sides in an isosceles triangle. Vertex Angle leg base

10. Base Angles

11. The two angles formed by the base and one of the congruent sides.

12. Base Angles The two angles formed by the base and one of the congruent sides. Base Angles leg base

13. Theorem 4.9 Isosceles Triangle Theorem

14. If two sides of a triangle are congruent, then the angles opposite those sides are congruent.

15. A B C D E

16. Theorem 4.10

17. If two angles of a triangle are congruent, then the sides opposite those angles are congruent.

18. L P Name two congruent angles. M N

19. L P Name two congruent segments. M N

20. Corollary 4.3

21. A triangle is equilateral if it is equiangular.

22. Corollary 4.4

23. Each angle of an equilateral triangle measures 60°.

24. E H FG J

25. E H FG J

26. E H FG J

27. Assignment: Pgs. 219-221 10-14 evens, 15-28 all, 44-46 evens