Parallel and Perpendicular Lines

Front

What are parallel lines?

Back

Lines that never intersect and have the same slope.

Front

What are perpendicular lines?

Back

Lines that intersect at a right angle (90 degrees) and have slopes that are opposite reciprocals.

Front

What is the slope of a line?

Back

The ratio of the rise (change in y) to the run (change in x) between two points on the line.

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.

Front

What is the slope of a line that is perpendicular to a line with a slope of 3?

Back

The slope of the perpendicular line is -1/3.

Front

What are opposite reciprocals?

Back

Two numbers whose product is -1; for example, 2 and -1/2.

Front

Write the equation of a line parallel to y = 2x + 1 that passes through the point (1, 3).

Back

y - 3 = 2(x - 1).

Front

Write the equation of a line perpendicular to y = -4x + 5 that passes through the point (2, 1).

Back

y - 1 = 1/4(x - 2).

Front

What is the slope-intercept form of a line?

Back

The slope-intercept form is y = mx + b, where m is the slope and b is the y-intercept.