Parallel and Perpendicular Lines

Front

What are parallel lines?

Back

Parallel lines are lines in a plane that never meet or intersect. 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

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

Back

They are parallel.

Front

What is the slope of a line perpendicular to a line with a slope of 2?

Back

-1/2 (the negative reciprocal of 2).

Front

If the slope of one line is 3, what is the slope of a line that is perpendicular to it?

Back

-1/3.

Front

What is the relationship between the slopes of parallel lines?

Back

The slopes of parallel lines are equal.

Front

What is the relationship between the slopes of perpendicular lines?

Back

The product of their slopes is -1.

Front

Given the equations y = 4x + 1 and y = 4x - 5, are these lines parallel, perpendicular, or neither?

Back

Parallel.

Front

Given the equations y = -1/2x + 3 and y = 2x - 1, are these lines parallel, perpendicular, or neither?

Back

Perpendicular.

Front

What is the slope of a line that is perpendicular to a line with a slope of -5?

Back

1/5.