LESSON 1–4 Angle Measure

Five-Minute Check (over Lesson 1–3) TEKS Then/Now New Vocabulary Example 1: Real-World Example: Angles and Their Parts Key Concept: Classify Angles Example 2: Measure and Classify Angles Example 3: Measure and Classify Angles Lesson Menu

Use the number line to find the measure of AC. 5-Minute Check 1

Use the number line to find the measure of DE. C. 7 D. 9 5-Minute Check 2

Use the number line to find the midpoint of EG. A. D B. E C. F D. H 5-Minute Check 3

Find the distance between P(–2, 5) and Q(4, –3). 5-Minute Check 4

Find the coordinates of R if M(–4, 5) is the midpoint of RS and S has coordinates (0, –10). B. (–4, 15) C. (–2, –5) D. (2, 20) 5-Minute Check 5

A boat located at (4, 1) can dock at two locations A boat located at (4, 1) can dock at two locations. Location A is at (–2, 9) and Location B is at (9, –11). Which location is closest? How many units away is the closest dock? A. Location A, 10 units B. Location A, 12.5 units C. Location B, 10 units D. Location B, 12.5 units 5-Minute Check 6

Mathematical Processes G.1(D), Also addresses G.1(E) Targeted TEKS G.5(B) Construct congruent segments, congruent angles, a segment bisector, an angle bisector, perpendicular lines, the perpendicular bisector of a line segment, and a line parallel to a given line through a point not on a line using a compass and a straightedge. Mathematical Processes G.1(D), Also addresses G.1(E) TEKS

You measured line segments. Measure and classify angles. Identify and use congruent angles and the bisector of an angle. Then/Now

ray degree right angle acute angle opposite rays angle obtuse angle angle bisector opposite rays angle side vertex interior exterior Vocabulary

A. Name all angles that have B as a vertex. Angles and Their Parts A. Name all angles that have B as a vertex. Answer: Example 1

Angles and Their Parts B. Name the sides of 5. Answer: Example 1

Angles and Their Parts C. Example 1

A. A. B. C. D. Example 1a

B. A. B. C. D. none of these Example 1b

Which of the following is another name for 3? B. C. D. Example 1c

Concept

A. Measure TYV and classify it as right, acute, or obtuse. Measure and Classify Angles A. Measure TYV and classify it as right, acute, or obtuse. Answer: mTYV = 90, so TYV is a right angle. Example 2

Answer: 180 > mWYT > 90, so WYT is an obtuse angle. Measure and Classify Angles Answer: 180 > mWYT > 90, so WYT is an obtuse angle. Example 2

Measure and Classify Angles Example 2

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

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

C. Measure DZX and classify it as right, acute, or obtuse. A. 30°, acute B. 30°, obtuse C. 150°, acute D. 150°, obtuse Example 2c

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 mGBH and mHCI if GBH  HCI, mGBH = 2x + 5, and mHCI = 3x – 10. Example 3

mGBH = mHCI Definition of congruent angles Measure and Classify Angles Step 1 Solve for x. GBH  HCI Given mGBH = mHCI 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

Step 2 Use the value of x to find the measure of either angle. Measure and Classify Angles Step 2 Use the value of x to find the measure of either angle. . Answer: mGBH = 35, mHCI = 35 Example 3

Find mBHC and mDJE if BHC  DJE, mBHC = 4x + 5, and mDJE = 3x + 30. A. mBHC = 105, mDJE = 105 B. mBHC = 35, mDJE = 35 C. mBHC = 35, mDJE = 105 D. mBHC = 105, mDJE = 35 Example 3

LESSON 1–4 Angle Measure