Example 1: Naming Angles Key Concept: Types of Angles Main Idea New Vocabulary Example 1: Naming Angles Key Concept: Types of Angles Example 2: Classify Angles Example 3: Classify Angles Key Concept: Pairs of Angles Example 4: Classify Angles Example 5: Classify Angles Example 6: Real-World Example Lesson Menu
Classify and determine the measure of angles. Main Idea/Vocabulary
angle vertex degrees right angle acute angle obtuse angle straight angle vertical angles adjacent angles complementary angles supplementary angles Main Idea/Vocabulary
Answer: The angle can be named in four ways: XYZ or ZYX, Y, or 1. Naming Angles Name the angle. ● Use the vertex as the middle letter and a point from each side. XYZ or ZYX ● Use the vertex only. Y ● Use a number. 1 Answer: The angle can be named in four ways: XYZ or ZYX, Y, or 1. Example 1
Name the angle. A. ACB or BCA, C, or 2 B. CAB or CAB, A, or 2 C. ABC or CBA, B, or 2 D. CBC or CAB, B, or 2 Example 1 CYP
Key Concept 2
Classify the angle as acute, obtuse, right, or straight. Classify Angles Classify the angle as acute, obtuse, right, or straight. Answer: The angle is between 90° and 180°, so it is an obtuse angle. Example 2
Classify the angle as acute, obtuse, right, or straight. A. acute B. obtuse C. right D. straight Example 2 CYP
Classify the following angle as acute, obtuse, right, or straight. Classify Angles Classify the following angle as acute, obtuse, right, or straight. Answer: The angle is exactly 180°, so the angle is straight. Example 3
Classify the following angle as acute, obtuse, right, or straight. A. acute B. obtuse C. right D. straight Example 3 CYP
Key Concept 2
Classify Angles Identify the following pair of angles as complementary, supplementary, or neither. Answer: The sum of the two angles is 180°, so the angles are supplementary. Example 4
Identify the following pair of angles as complementary, supplementary, or neither. A. complementary B. supplementary C. neither Example 4 CYP
Classify Angles Identify the following pair of angles as complementary, supplementary, or neither. Answer: The sum of the two angles is 140°, so they are neither complementary nor supplementary. Example 5
Identify the following pair of angles as complementary, supplementary, or neither. A. complementary B. supplementary C. neither Example 5 CYP
TIME The hour, minute, and second hands make up two adjacent angles that form a right angle in the clock shown below. Find the missing angle. Example 6
first angle second angle Write an equation. first angle second angle x + 72 = 90 Solve the equation. x + 72 = 90 Write the equation. – 72 = – 72 Subtract 72 from each side. x = 18 Simplify. Answer: So, the value of x is 18. Example 6
TIES The two adjacent angles in the ties form a right angle TIES The two adjacent angles in the ties form a right angle. Find the missing angle measure. A. 45° B. 90° C. 135° D. 145° Example 6 CYP