1. A NSWERS TO E VENS 2) FE||CD4) FB||EC 6) AE||BC8) None 10) AE||BD12) FB||EC 14) None16) AE||BD and AB||FC 18) x = 90, y = 13020) PQ||RS 24) Given Definition Angle Bisector Substitution/Transitive Alternate int. angles are cong., then lines are ||.

2. 3-4 A NGLES OF TRIANGLES

3. TYPES OF TRIANGLES (BY SIDES ) ScaleneIsosceles Equilateral No congruent sides 2 congruent sides 3 congruent sides

4. TYPES OF TRIANGLES (BY ANGLES ) AcuteObtuse RightEquiangular All acute angles1 obtuse angle 3 congruent angles 1 right angle

5. T ERMS TO K NOW B A C Vertices (plural) A B C TRIANGLE ABC Angles: A, B, C

6. T HEOREM The sum of the measures of the angles of a triangle is 180º All 3 angles must = 180 (Like Ang. Add. Post)

7. C OROLLARY (something that can be proven from a theorem) If 2 angles of a triangle are cong. to 2 angles of another triangle, then the 3 rd angles are also congruent. BA C YX Z

8. C OROLLARY Each angle of an equiangular triangle is 60º. In a triangle, there can be at most 1 right or 1 obtuse angle. Acute angles of a right triangle are complementary.

9. EXTERIOR ANGLE THEOREM The measure of an exterior angle of a triangle equals the sum of the measures of the two remote interior angles 70 30 80 100 Remote Interior Angles Exterior Angle

10. TOO Page 96 #9-11 Answers 9) 90° 10) 105° 11) 75° Homework: Page 97 #1-20, 25 25: 5 steps, separate the triangles! Flashcards: Both Theorems and any of the triangles that you did not already know.