Classifying angles

Front

What is an angle?

Back

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

Front

What is the measure of a right angle?

Back

A right angle measures exactly 90 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 straight angle?

Back

A straight angle is an angle that measures exactly 180 degrees.

Front

What are vertical angles?

Back

Vertical angles are the angles opposite each other when two lines intersect. They are always congruent (equal in measure).

Front

What is the sum of angles in a triangle?

Back

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

Front

What is a complementary angle?

Back

Complementary angles are two angles whose measures add up to 90 degrees.

Front

What is a supplementary angle?

Back

Supplementary angles are two angles whose measures add up to 180 degrees.

Front

How do you find a missing angle in a triangle?

Back

To find a missing angle in a triangle, subtract the sum of the known angles from 180 degrees.