Download Geometry 4.2 student copy

4-2
Angle Relationships in Triangles
Objectives
Find the measures of interior and exterior
angles of triangles.
Apply theorems about the interior and exterior
angles of triangles.
Vocabulary
Holt Geometry
4-2
Angle Relationships in Triangles
B
1
A
Holt Geometry
2
C
4-2
Angle Relationships in Triangles
Practice
1. Use the diagram to find m∠MJK.
1.5 For Fun find m∠L = ?
Holt Geometry
4-2
Angle Relationships in Triangles
A corollary is a theorem whose proof follows directly from another
theorem. Here are two corollaries to the Triangle Sum Theorem.
Holt Geometry
4-2
Angle Relationships in Triangles
Practice: Finding Angle Measures in Right Triangles
2. The measure of one of the acute angles in a right triangle is
63.7°. What is the measure of the other acute angle?
Holt Geometry
4-2
Angle Relationships in Triangles
Practice
3. The measure of one of the acute angles in a right triangle is
2°
48 5 . What is the measure of the other acute angle?
4. One of the acute angles in a right triangle measures 2x°.
What is the measure of the other acute angle?
Holt Geometry
4-2
Angle Relationships in Triangles
Interior
Holt Geometry
Exterior
4-2
Angle Relationships in Triangles
Practice: Applying the Exterior Angle Theorem
5. Find m∠B.
Holt Geometry
6. Find m∠ACD.
4-2
Holt Geometry
Angle Relationships in Triangles
4-2
Angle Relationships in Triangles
Practice: Applying the Third Angles Theorem
7. Find m∠K and m∠J.
Holt Geometry
4-2
Angle Relationships in Triangles
Practice
8. Find m∠P and m∠T.
Holt Geometry