Parallel and Perpendicular Lines

Front

What are parallel lines?

Back

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

Front

What are 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 line #1 is 2, what is the slope of a line that is perpendicular to it?

Back

The slope of the perpendicular line would be -1/2.

Front

If two lines have the same slope, what can we conclude about them?

Back

The lines are parallel.

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

Given the slopes of two lines, how can you determine if they are perpendicular?

Back

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

Front

If line #1 has a slope of 3 and line #2 has a slope of 3, what is the relationship between the two lines?

Back

The lines are parallel.

Front

What is the relationship between the slopes of two lines that are neither parallel nor perpendicular?

Back

The slopes are neither equal nor negative reciprocals.

Front

If the slope of line #1 is 4, what is the slope of a line that is parallel to it?

Back

The slope of the parallel line would also be 4.