6.4.2 I can describe figures by using the terms of geometry

8.1 Building Blocks of Geometry

Vocabulary

pointlineplaneline segmentray

Use the diagram to name the geometric figure.

A. three points

B. two lines V

S

U

WT

Use the diagram to give a possible name to the figure.

A. three different line segments

B. three ways to name the line

C

A B

Lesson Quiz

Use the diagram to name each geometric figure.

1. three points

2. two lines

3. a point shared by a line and a ray

4. a plane

Possible answer: A, B, C

Possible answer: F

Possible answer: plane AEC

Possible answer: AD, CE

6.4.2 I can name, measure, draw, and classify angles

8.2 Measuring and Classifying Angles

Vocabulary

anglevertexacute angleright angleobtuse anglestraight angle

An acute angle measures greater than 0° and less than 90°.

A right angle measures exactly 90°.

Right angles are usually marked with a symbol.

Reading Math

An obtuse angle measures greater than 90° and less than 180°.

A straight angle measures exactly 180°.

Additional Example 3: Classifying Angles

Classify each angle as acute, right, obtuse, or straight.

A. B.

The angle measures less than 90°, so it is an acute angle.

The angle measures exactly 90°, so it is a right angle.

Check It Out: Example 3

Classify each angle as acute, right, obtuse, or straight.

A. B.

The angle measures less than 90°, so it is an acute angle.

The angle measures exactly 180°, so it is a straight angle.