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 but different y-intercepts.

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

How do you determine if two lines are parallel?

Back

Two lines are parallel if they have the same slope.

Front

How do you determine if two lines are perpendicular?

Back

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

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Back

Front

Back

Front

Back

They are parallel because they have the same slope of 2.

Front

Back

They are perpendicular because the product of their slopes (1/3 and -3) is -1.

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Back

The slope of the line is 5.

Front

If a line has a slope of 4, what is the slope of a line that is perpendicular to it?

Back

The slope of a line that is perpendicular to it is -1/4.