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Dihedral Angle

The Angle between two Planes. The dihedral angle between the planes

$\displaystyle A_1x+B_1y+C_1z+D_1$ $\textstyle =$ $\displaystyle 0$ (1)
$\displaystyle A_2x+B_2y+C_2z+D_2$ $\textstyle =$ $\displaystyle 0$ (2)

is
\begin{displaymath}
\cos\theta={A_1A_2+B_1B_2+C_1C_2\over\sqrt{{A_1}^2+{B_1}^2+{C_1}^2}\sqrt{{A_2}^2+{B_2}^2+{C_2}^2}}.
\end{displaymath} (3)

See also Angle, Plane, Vertex Angle




© 1996-9 Eric W. Weisstein
1999-05-24