Equations of Parallel and Perpendicular Lines

Front

PERPENDICULAR lines have slopes that are ___________________.

Back

opposite reciprocals

Front

PARALLEL lines have slopes that are ___________________.

Back

the same

Front

What is the slope of a line parallel to the line y = 2x + 3?

Back

2

Front

What is the slope of a line perpendicular to the line y = -3x + 1?

Back

1/3 (the opposite reciprocal of -3)

Front

If two lines have slopes m1 and m2, and m1 * m2 = -1, what can be said about the lines?

Back

They are perpendicular.

Front

If two lines have the same slope, what can be said about them?

Back

They are parallel.

Front

What is the slope of the line represented by the equation 4x - 2y = 8?

Back

2 (rewriting in slope-intercept form gives y = 2x - 4)

Front

How do you find the slope of a line given two points (x1, y1) and (x2, y2)?

Back

Slope (m) = (y2 - y1) / (x2 - x1)