Angle Relationships in Triangles

1. Angle Relationships in Triangles Geometry 4.2

2. Remember! The sum of the angle measures of a triangle is 180° This is for every triangle

3. Remember! Order matters with congruency statements. Means: A and E correspond B and F correspond C and G correspond

4. Remember! • The Bigger an angle is, the larger the side opposite! • The smaller an angle is, the smaller the side opposite! Middle Biggest Shortest Middle Middle Smallest Longest Longest Shortest Biggest Smallest Middle

5. Auxiliary Line • An auxiliary line is a line that is added to the figure to aid in the proof

6. Corollary • A corollary is a theorem whose proof follows directly from another theorem.

7. Interior vs. Exterior • The interior is the set of all points inside the figure. • The exterior is the set of all points outside the figure.

8. Interior vs. Exterior Angles 4 is an exterior angle. 3 is an interior angle.

9. Remote Interior Angle 4 is an exterior angle.

10. Theorem 50° 50° 100°

11. Example Find the measure of <B

12. Example Find the measure of <ACD

13. Theorem

14. Example Find measure of <K and <J

15. Example Find measure of <P and <T

16. Class work • Page 227: • 6, 7, 9-14, 19, 35