Perpendicular Distance

In geometry, the perpendicular distance from a point, P, to a line, L, is the distance from P to L, measured along a line which is perpendicular to L and passes through P.

In three dimensions, a perpendicular distance may also be the distance from a point to a plane, measured along the line that passes through the point and is perpendicular to the plane. Also, it can be the distance between two non-coplanar lines, measured along the line that has perpendicular intersections with them both.