Khan Academy
Khan Academy: Algebra: Perpendicular Lines 2
This video demonstrates how to find the equation of a line when given a point on the line and the equation of a line perpendicular to it. Practice problems available. [3:01]
Khan Academy
Khan Academy: More Analytic Geometry: Perpendicular Lines 2
This video demonstrates how to find the equation of a line when given a point on the line and the equation of a line perpendicular to it.