Distance from a point to a plane

In Euclidean space, the distance from a point to a plane is the distance between a given point and its orthogonal projection on the plane, the perpendicular distance to the nearest point on the plane.

It can be found starting with a change of variables that moves the origin to coincide with the given point then finding the point on the shifted plane ${\displaystyle ax+by+cz=d}$ that is closest to the origin. The resulting point has Cartesian coordinates ${\displaystyle (x,y,z)}$:

${\displaystyle \displaystyle x={\frac {ad}{a^{2}+b^{2}+c^{2}}},\quad \quad \displaystyle y={\frac {bd}{a^{2}+b^{2}+c^{2}}},\quad \quad \displaystyle z={\frac {cd}{a^{2}+b^{2}+c^{2}}}}$.

The distance between the origin and the point ${\displaystyle (x,y,z)}$ is ${\displaystyle {\sqrt {x^{2}+y^{2}+z^{2}}}}$.