Chapter 1.4

Angle Measure

Vocabulary

Ray – part of a line that has one endpoint and extends indefinitely in one direction.

Opposite Rays – two rays that share a common endpoint and are collinear

Angle – formed by two noncollinear rays (sides) that share a common endpoint (vertex). There is an interior of each angle and an exterior of each angle.

Example 1 Angles and Their Parts

A. Name all angles that have B as a vertex.

Answer:

Example 1 Angles and Their Parts

Answer:

B. Name the sides of 5.

Example 1 Angles and Their Parts

C.

Example 1a

A.

B.

C.

D.

Example 1b

A.

B.

C.

D. none of these

A.

B.

C.

D.

Example 1c

Which of the following is another name for 3?

Concept

Measure and Classify Angles

A. Measure TYV and classify it as right, acute, or obtuse.

Answer: mTYV = 90, so TYV is a right angle.

Measure and Classify Angles

Answer: 180 > mWYT > 90, so WYT is an obtuse angle.

Measure and Classify Angles

Protractor Time!

Measure an angle

Create an angle

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.

A. mBHC = 105, mDJE = 105

B. mBHC = 35, mDJE = 35

C. mBHC = 35, mDJE = 105

D. mBHC = 105, mDJE = 35

Find mBHC and mDJE if BHC DJE, mBHC = 4x + 5, and mDJE = 3x + 30.