1. 4.7.1 USE ISOSCELES AND EQUILATERAL TRIANGLES Chapter 4: Congruent Triangles SWBAT: Define Vertex angle, leg, base, and base angle. State, prove, and use the base angle theorem and converse You will accomplish this on slide 5 and on homework problems

2. Isosceles Triangles We know SAS and ASA so for Isosceles Triangles we have many possiblities. Certain theorems can state short cuts for us for when we are proving triangles that are Isosceles congruent.

3. Vocab: Legs: two sides of an Isosceles triangle that are congruent Base: the side of an Isosceles triangle that is not congruent to the other two Base angles: the two angles that are congruent in an Isosceles triangle Vertex angle: the third angle that is not congruent to the other two Vertex Angle Base Legs Base Angles Isosceles Triangle:

4. Base Angle Theorem: If two sides of a triangle are congruent then the two angles opposite them are congruent Converse of the Base Angle Theorem: If two angles of a triangle are congruent then the two sides opposite them are congruent Given:Then:Given:Then:

5. Measurement Given  ABC and  ABE are Isosceles Triangles Given m  ACB = 10 ⁰ And AB  AC  AE Find x and y if m  AEB = (3x – y) ⁰ m  BAE = (6x + 2y) ⁰ A B C D E

6. Homework P. 267 1 – 6, 12, 13, 15, 19, 26, 41, 48