Likewise, the distance from a point to a curve is measured by a line segment that is perpendicular to a tangent line to the curve at the nearest point on the curve.
The distance from a point to a plane is measured as the length from the point along a segment that is perpendicular to the plane, meaning that it is perpendicular to all lines in the plane that pass through the nearest point in the plane to the given point.
Other instances include: Perpendicular regression fits a line to data points by minimizing the sum of squared perpendicular distances from the data points to the line.
Other geometric curve fitting methods using perpendicular distance to measure the quality of a fit exist, as in total least squares.
The concept of perpendicular distance may be generalized to