Slopes of Parallel and Perpendicular Lines

Front

What is the definition of parallel lines?

Back

Parallel lines are lines in a plane that never meet. They have the same slope.

Front

What is the definition of perpendicular lines?

Back

Perpendicular lines are lines that intersect at a right angle (90 degrees). The slopes of perpendicular lines are negative reciprocals of each other.

Front

If the slope of a line is m, what is the slope of a line parallel to it?

Back

The slope of a line parallel to it is also m.

Front

If the slope of a line is m, what is the slope of a line perpendicular to it?

Back

The slope of a line perpendicular to it is -1/m.

Front

What is the slope of a horizontal line?

Back

The slope of a horizontal line is 0.

Front

What is the slope of a vertical line?

Back

The slope of a vertical line is undefined.

Front

How do you determine if two lines are parallel using their slopes?

Back

Two lines are parallel if their slopes are equal.

Front

How do you determine if two lines are perpendicular using their slopes?

Back

Two lines are perpendicular if the product of their slopes is -1.

Front

What is the slope of a line that rises from left to right?

Back

The slope of a line that rises from left to right is positive.

Front

What is the slope of a line that falls from left to right?

Back

The slope of a line that falls from left to right is negative.