Section 1.4: Angle Measure

Vocab VocabularyDefinitionPicture Ray Named by: Two letters Opposite Rays Angle Named By : Three letters Formed by two rays that have a common endpoint.

Vocab Sides Vertex Interior of the Angle Exterior of the Angle. The rays of an angle are called sides. The vertex is the common endpoint. Points that lie on the inside of an angle. Ex: points S and R Points that lie on the outside of an angle. Ex: points P and O

Example 1 Use the diagram below. a) Name all angles that have B as a vertex. b) Name the sides of angle 5. c) Write another name for angle 6.

Example 2 a)Name all angles that have B as a vertex. b)Name the sides of Angle 3. c) What is another name of Angle GHL? d) Name a point in the interior of Angle DBK.

Vocab VocabularyDefinitionPicture Right Angle Symbol that indicates a 90 degree angle : Acute Angle Obtuse Angle Congruent Angles Symbol that indicates congruent angles: An angle that measures exactly 90◦ An angle that measures less than 90◦ An angle that measures greater than 90◦ Angles that have the exact same measure.

Example 3

Brain Break!

Vocab VocabularyDefinitionPicture Angle bisector A ray that divides an angle into two congruent angles.

Example 4

Example 5