Knowing that parallel lines have the same slope allows you to solve some problems involving parallel lines.

Example 1

Determine an equation for a line that is parallel to «math style=¨font-family:`Times New Roman`¨ xmlns=¨http://www.w3.org/1998/Math/MathML¨»«mi»y«/mi»«mo»=«/mo»«mn»3«/mn»«mi»x«/mi»«mo»+«/mo»«mn»9«/mn»«/math» and passes through the point (2,−6).

The slope of the original line is 3, so the parallel line must also have a slope of 3. Knowing both the slope and a point on the line is enough information to write an equation for the new line, using the slope-point form.