Article / Updated 12-08-2016
In coordinate geometry, there are different line equations you can use, depending on whether a line is horizontal, vertical, or at an angle, and whether you know the line's y-intercept. Here are the basic forms for equations of lines: Slope-intercept form. Use this form when you know (or can easily find) a line's slope and its y-intercept (the point where the line crosses the y-axis).