Using a Protractor

Front

What tool do we use to measure angles?

Back

Protractor

Front

Fill in the blank. This angle measures ___ degrees.

Back

120

Front

What is an angle?

Back

An angle is formed by two rays that meet at a point called the vertex.

Front

What is the vertex of an angle?

Back

The vertex is the point where two rays meet to form an angle.

Front

What are the two rays in an angle called?

Back

The two rays are called the sides of the angle.

Front

What is a right angle?

Back

A right angle measures 90 degrees.

Front

What is an acute angle?

Back

An acute angle measures less than 90 degrees.

Front

What is an obtuse angle?

Back

An obtuse angle measures more than 90 degrees but less than 180 degrees.

Front

How do you use a protractor to measure an angle?

Back

Align the midpoint of the protractor with the vertex of the angle and read the measurement where one side crosses the number scale.

Front

What is a straight angle?

Back

A straight angle measures exactly 180 degrees.