Direction Cosines of a Plane Normal

Direction Cosines of a Plane Normal

For plane:

$$Ax+By+Cz+D=0$$

the direction cosines of its normal are proportional to:

$$A:B:C$$

Hence:

$$l=\frac{A}{\sqrt{A^2+B^2+C^2}}$$

$$m=\frac{B}{\sqrt{A^2+B^2+C^2}}$$

$$n=\frac{C}{\sqrt{A^2+B^2+C^2}}$$

Usage

- Used to determine the orientation of the normal to a plane.