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This comprehensive lesson focuses on measuring and classifying angles, including right, acute, and obtuse angles. Students will learn to identify and utilize congruent angles and angle bisectors. Key concepts include understanding the vocabulary related to angles and their parts, measuring angles accurately, and applying knowledge to solve problems. Through examples, learners will practice determining angle measures and relationships, fostering skills in geometry applicable to various real-world scenarios.
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You measured line segments. (Lesson 1–2) • Measure and classify angles. • Identify and use congruent angles and the bisector of an angle. Then/Now
degree • right angle • acute angle • obtuse angle • angle bisector • ray • opposite rays • angle • side • vertex • interior • exterior Vocabulary
Answer: Angles and Their Parts A. Name all angles that have B as a vertex. Example 1
Answer: Angles and Their Parts B.Name the sides of5. Example 1
C. Angles and Their Parts Example 1
A B C D A. B. C. D. A. Example 1a
A B C D A. B. C. D. none of these B. Example 1b
A B C D A. B. C. D. Which of the following is another name for 3? C. Example 1c
Measure and Classify Angles A. Measure TYV and classify it as right, acute, or obtuse. Answer:mTYV = 90, so TYV is a right angle. Example 2
Measure and Classify Angles Example 2
A B C D A.Measure CZD and classify it as right, acute, or obtuse. A. 30°, acute B. 30°, obtuse C. 150°, acute D. 150°, obtuse Example 2a
A B C D B.Measure CZE and classify it as right, acute, or obtuse. A. 60°, acute B. 90°, acute C. 90°, right D. 90°, obtuse Example 2b
Measure and Classify Angles INTERIOR DESIGN Wall stickers of standard shapes are often used to provide a stimulating environment for a young child’s room. A five-pointed star sticker is shown with vertices labeled. Find mGBH and mHCI if GBH HCI, mGBH = 2x + 5, and mHCI =3x – 10. Example 3
Measure and Classify Angles Step 1 Solve for x. GBH HCI Given mGBH mHCI Definition of congruent angles 2x + 5 = 3x – 10 Substitution 2x + 15 = 3x Add 10 to each side. 15 = x Subtract 2x from each side. Example 3
. Measure and Classify Angles Step 2 Use the value of x to find the measure of either angle. Answer:mGBH = 35, mHCI = 35 Example 3
A B C D Find mBHC and mDJE if BHC DJE, mBHC = 4x + 5, and mDJE = 3x + 30. A.mBHC = 105, mDJE = 105 B.mBHC = 35, mDJE = 35 C.mBHC = 35, mDJE = 105 D.mBHC = 105, mDJE = 35 Example 3