What are the characteristics of Lines in the Plane? Section P4 (new text)

Slope The slope of the nonvertical line through the points (x 1, y 1 ) and (x 2, y 2 ) is If the line is vertical, then x 1 = x 2 and the slope is undefined.

Example Find the slope of the line between these points.

Point-Slope Form The point-slope form of an equation of a line that passes through the point (x 1, y 1 ) and has the slope m is

Example Use Point-Slope form to find an equation of the line that passes through the following point with the given slope. Put your answer in Slope-Intercept form.

Slope-Intercept Form The slope-intercept form of an equation of a line with slope m and y-intercept (0, b) is

General & Standard Form General Form (A and B not both zero) Standard Form (A and B not both zero)

Intercepts X-intercept— Y-intercept— You can find the intercepts and use them to graph the line. Where the line crosses the x-axis (y = 0) Where the line crosses the y-axis (x = 0)

Parallel and Perpendicular Lines Parallel lines have equal slopes. Perpendicular lines have opposite, reciprocal slopes