1. CH. 4.7 USE ISOSCELES & EQUILATERAL TRIANGLES

2. VOCAB Leg: 2 sides of isosceles triangle Leg Vertex Angle: Angle formed by the two legs Base: 3 rd side of the isosceles angle Base Angles Base Angles: 2 angles adjacent to the base.

3. THEOREM 4.7: BASE ANGLES THEOREM If two sides of a triangle are congruent, then the angles opposite them are congruent. C A B

4. THEOREM 4.7: BASE ANGLES THEOREM If two sides of a triangle are congruent, then the angles opposite them are congruent. C A B <C

5. THEOREM 4.7: BASE ANGLES THEOREM EX C A B 88 72x

6. THEOREM 4.7: BASE ANGLES THEOREM EX C A B 110 yx

7. THEOREM 4.7: BASE ANGLES THEOREM EX C A B y x + 755

8. THEOREM 4.8: CONVERSE OF BASE ANGLES THEOREM If two angles of a triangle are congruent, then the sides opposite them are congruent. C A B

9. THEOREM 4.8: CONVERSE OF BASE ANGLES THEOREM If two angles of a triangle are congruent, then the sides opposite them are congruent. C A B AC

10. THEOREM 4.7: BASE ANGLES THEOREM EX C A B X8 72

11. COROLLARY TO THE BASE ANGLES THEOREM If a triangle is equilateral, then it is ________. C A B COROLLARY TO THE CONVERSE OF BASE ANGLES THEOREM If a triangle is equiangular, then it is _______.

12. COROLLARY TO THE BASE ANGLES THEOREM If a triangle is equilateral, then it is ____________________. C A B COROLLARY TO THE CONVERSE OF BASE ANGLES THEOREM If a triangle is equiangular, then it is ________________. equiangular equilateral

13. EX. C A B 70?

14. EX. C A B 70? Since it is an ISOSCELES triangle <B = <C So, <C = 70

15. EX. C A B 5x 10

16. EX. C A B 40 11x-18

17. EX. C A B 12x+22 6y-5 10y-41