1. 4.1 Triangles and Angles Interior and Exterior Angles Types of Triangles

2. Definition of a triangle A triangle is three segments joined at three noncollinear end points.

3. Types of Triangles by Sides 3 Sides congruent → Equilateral

4. Types of Triangles by Sides 2 Sides congruent → Isosceles Part of the Isosceles Triangle

5. Types of Triangles by Sides No Sides congruent → Scalene

6. Types of Triangles by Sides 3 Sides congruent → Equilateral 2 Sides congruent → Isosceles No Sides congruent → Scalene

7. Types of Triangle by Angles All Angles less than 90 degrees → Acute

8. Types of Triangle by Angles One Angle greater than 90 degrees → Obtuse

9. Types of Triangle by Angles One Angle equal to 90 degrees → Right

10. Parts of the Right Triangle Across from the right angle is the hypotenuse.

11. Equiangluar All the angles are Equal

12. Interior Angles vs. Exterior Angles Interior Angles in Pink Exterior Angles In light green

13. A Theorem about Angles in a Triangle The interior angles in a triangle add to 180º Solve for x

14. Theorem about an exterior angle The measure of an exterior angle equals the measure of the two nonadjecent interior angles.

15. Solve for x

16. Corollary for the fact that interior angles add to 180º The acute angles of a Right triangle are complementary.

17. Homework Page 198 - 201 # 10 - 15, 16 - 38 even, 42, 49, 50

18. Homework Page 198 - 201 # 17 – 43 odd, 45 – 47, 52 - 68