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). The slopes of perpendicular lines are negative reciprocals of each other.

Front

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

Back

If two lines have the same slope, they are parallel.

Front

If the slopes of two lines are m1 and m2, and m1 * m2 = -1, what can we conclude?

Back

The lines are perpendicular.

Front

What is the slope of a line that is vertical?

Back

The slope of a vertical line is undefined.

Front

What is the slope of a line that is horizontal?

Back

The slope of a horizontal line is 0.

Front

Given the slopes of line #1 = 3 and line #2 = 3, are the lines parallel, perpendicular, or neither?

Back

The lines are parallel.

Front

Given the slopes of line #1 = 2 and line #2 = -1/2, are the lines parallel, perpendicular, or neither?

Back

The lines are perpendicular.

Front

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

Back

The slopes of the lines do not satisfy the conditions for parallelism (same slope) or perpendicularity (negative reciprocals).

Front

If line #1 has a slope of 5 and line #2 has a slope of -1/5, what is the relationship between the two lines?

Back

The lines are perpendicular.