1. Warm-up Finish the back page of your homework!!! 15 minutes if you are done early you need to compare answers with a neighbor/friend

2. Warm-up Label the following triangles by their sides and angles

3. Today Warm-up Quiz Objective Notes Practice Problems

4. Geometry 4.3: Isosceles and Equilateral Triangles Objective: _______________________________ _____________________________

5. Parts of an Isosceles Triangle Legs: Congruent Sides Base: Non-congruent side Base Angles: 2 angles at the base of the triangle

6. Isosceles Triangle 1. Use a ruler to draw a isosceles triangle on patty paper 1.The congruent sides need to be 4 inches long 2. Draw an arc on one of the base angles. 3. Fold the patty paper so that the crease is down the middle of the triangle going trough the base. 4. Line up the angles What do you notice about the to base angles?

7. Equilateral Triangles 1. Use a ruler to draw a Equilateral triangle on patty paper 1.All of the sides need to be 4 inches long 1.Start with the base, at the two inches put a mark 2.Draw a line perp. to the base from the 2 inch mark 3.Draw the two other sides 4 inches long touching that middle line. 2. Draw an arc the one of the angles. 3. Fold the patty paper so that the crease is down the middle of the triangle. 4. Line up the angles. 5. Try folding again using a different set of angles. What do you notice about the to angles?

8. Base Angle Theorem: If two sides of a triangle are congruent, then the angles opposite them are congruent. If AB = AC, then __________

9. Practice:

10. Converse of the Base Angles Theorem: If two angles of a triangle are congruent, then the sides opposite them are congruent. If <B = <C, then _____

11. Practice

12. Equilateral Triangle Theorem: If a triangle is equilateral, then it is equiangular. Equiangular Theorem: If a triangle is equiangular then it is equilateral.

13. Practice