Angle Basics

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 are perpendicular lines?

Back

Perpendicular lines are lines that intersect at a right angle (90 degrees).

Front

What are parallel lines?

Back

Parallel lines are lines in a plane that never meet and are always the same distance apart.

Front

What is a right angle?

Back

A right angle is an angle that 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 is a line?

Back

A line is a straight one-dimensional figure that extends infinitely in both directions.

Front

What is a line segment?

Back

A line segment is a part of a line that has two endpoints.

Front

What is a ray?

Back

A ray is a part of a line that has one endpoint and extends infinitely in one direction.