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). Their slopes are negative reciprocals of each other.

Front

What is the slope of a line perpendicular to y = mx + b?

Back

The slope of a line perpendicular to y = mx + b is -1/m.

Front

If two lines have slopes m1 and m2, when are they parallel?

Back

Two lines are parallel if m1 = m2.

Front

If two lines have slopes m1 and m2, when are they perpendicular?

Back

Two lines are perpendicular if m1 * m2 = -1.

Front

What is the slope of the line y = 2x - 7?

Back

The slope of the line y = 2x - 7 is 2.

Front

What is the slope of a line parallel to y = 2x - 7?

Back

The slope of a line parallel to y = 2x - 7 is also 2.

Front

What is the slope of a line perpendicular to y = 2x - 7?

Back

The slope of a line perpendicular to y = 2x - 7 is -1/2.

Front

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

Back

Two lines are neither parallel nor perpendicular if they intersect at an angle that is not 90 degrees and do not have the same slope.

Front

If the slopes of two lines are -6 and 6, what can we say about them?

Back

The lines are perpendicular because their slopes are negative reciprocals.