Parallel and Perpendicular Lines

Front

What are perpendicular lines?

Back

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

Front

What is the relationship between the slopes of two perpendicular lines?

Back

The slopes of two perpendicular lines are opposite reciprocals of each other.

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 the relationship between the slopes of two parallel lines?

Back

The slopes of two parallel lines are equal.

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 a line with slope m is -1/m.

Front

What is the slope of a line that is horizontal?

Back

The slope of a horizontal line is 0.

Front

What is the slope of a line that is vertical?

Back

The slope of a vertical line is undefined.

Front

If two lines have slopes of 2 and -1/2, are they perpendicular?

Back

Yes, because their slopes are opposite reciprocals.

Front

What does it mean for two lines to be neither parallel nor perpendicular?

Back

It means the lines intersect at an angle that is not 90 degrees and do not have equal slopes.

Front

How can you determine if two lines given by equations are parallel?

Back

If the coefficients of x in both equations are the same when in slope-intercept form (y = mx + b), the lines are parallel.