## Thomas' Calculus 13th Edition

Find ${\bf n}\times{\bf v}$ (or ${\bf v}\times{\bf n}$).
The vector ${\bf n}\times{\bf v}$ is perpendicular to both ${\bf n}$ and ${\bf v}$. One condition is obviously satisfied (perpendicular to ${\bf v}$). Being perpendicular to a vector that is perpendicular to the plane, the vector ${\bf n}\times{\bf v}$ lies in a plane parallel to our plane. Thus, the second condition is also satisfied.