Main Idea and New Vocabulary Key Concept: Types of Angles Example 1: Name Angles Key Concept: Pairs of Angles Example 2: Real-World Example Example 3: Find a Missing Angle Measure Lesson Menu
Classify angles and identify vertical and adjacent angles. congruent vertex acute angle right angle obtuse angle straight angle vertical angles adjacent angles Main Idea/Vocabulary
Key Concept
Since the angle is less than 90°, it is an acute angle. Name Angles Name the angle below in four ways. Then classify it as acute, right, obtuse, or straight. • Use the vertex as the middle letter and a point from each side, FGH or HGF. • Use the vertex only, G. • Use a number, 2. Since the angle is less than 90°, it is an acute angle. Example 1
Answer: FGH, HGF, G, 2; acute Name Angles Answer: FGH, HGF, G, 2; acute Example 1
Name the angle below in two ways Name the angle below in two ways. Then classify it as acute, right, obtuse, or straight. A. JKL, K; acute B. LKJ, K; right C. JKL, K; obtuse D. LKJ, J; obtuse Example 1 CYP
Key Concept 2
4 and 5 are adjacent angles because they share a common side. SEWING Identify a pair of vertical angles and adjacent angles in the diagram. Justify your response. Answer: 3 and 5 are vertical angles because they are opposite angles formed by intersecting lines. 4 and 5 are adjacent angles because they share a common side. Example 2
A. vertical: 5 and 7 adjacent: 5 and 8 HIKING Identify a pair of vertical angles and adjacent angles in the diagram of the hiking trails. A. vertical: 5 and 7 adjacent: 5 and 8 B. vertical: 5 and 8 adjacent: 6 and 7 C. vertical: 6 and 7 adjacent: 5 and 8 D. vertical: 6 and 7 adjacent: 7 and 8 Example 2 CYP
Find a Missing Angle Measure What is the value of y in the figure below? The angle labeled y and the angle labeled 60 are vertical angles. Since vertical angles are congruent, the value of y is 60. Answer: 60° Example 3
What is the value of x in the figure below? C. 104° D. 180° Example 3 CYP