Parallel and Perpendicular Lines

Front

What are parallel lines?

Back

Lines in a plane that never meet 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 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 parallel to y = 2x + 3?

Back

2

Front

What is the slope of a line perpendicular to y = -1/2x + 4?

Back

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

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).

Front

What is the equation of a line in slope-intercept form?

Back

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

Front

If the slope of a line is 0, what type of line is it?

Back

A horizontal line.

Front

If the slope of a line is undefined, what type of line is it?

Back

A vertical line.

Front

What is the relationship between the slopes of two perpendicular lines?

Back

The product of their slopes is -1.