Understanding Angles and Protractors

Front

What is an angle?

Back

An angle is formed by two rays (sides of the angle) that share a common endpoint (the vertex).

Front

What is a protractor used for?

Back

A protractor is a tool used to measure angles in degrees.

Front

What is the measure of a right angle?

Back

A right angle measures 90 degrees.

Front

What is the measure of a straight angle?

Back

A straight angle measures 180 degrees.

Front

What is an acute angle?

Back

An acute angle is an angle that measures less than 90 degrees.

Front

What is an obtuse angle?

Back

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

Front

What is a reflex angle?

Back

A reflex angle is an angle that measures more than 180 degrees but less than 360 degrees.

Front

What is the vertex of an angle?

Back

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

Front

How do you measure an angle using a protractor?

Back

Align the protractor's center point with the vertex of the angle, then read the measurement where one ray crosses the protractor's scale.

Front

What is the sum of angles in a triangle?

Back

The sum of the angles in a triangle is always 180 degrees.