Editing Cartesian coordinate system (section)

===Generalizations===
The concept of Cartesian coordinates generalizes to allow axes that are not perpendicular to each other, and/or different units along each axis. In that case, each coordinate is obtained by projecting the point onto one axis along a direction that is parallel to the other axis (or, in general, to the [[hyperplane]] defined by all the other axes). In such an ''[[oblique coordinate system]]'' the computations of distances and angles must be modified from that in standard Cartesian systems, and many standard formulas (such as the Pythagorean formula for the distance) do not hold (see [[affine plane]]).