A plane in three-space can be defined by one point in the plane and a normal vector orthogonal to the plane.

    Vector Equation of a Plane:

    Given a point P0(x0, y0, z0) in the plane and a normal vector n, let P(x, y, z) be an arbitrary point in the plane. Let r and r0 be the position vectors of P and P0 respectively. Subtracting r from r0 gives us a vector inside the plane, which is orthogonal to n. Thus:

    n . (r - r0) = 0

    or

    n . r = n . r0

    Scalar Equation of a Plane:

    Given a point P0(x0, y0, z0) in the plane and a normal vector n = , let P(x, y, z) be an arbitrary point in the plane. The vector equation then becomes:

    a(x-x0) + b(y-y0) + c(z-z0) = 0

    Linear Equation of a Plane:

    ax + by + cz = d

    where d = ax0 + by0 + cz0


This node made possible by Calculus Concepts and Contexts by James Stewart.