The angles $\phi$, $\psi$ and $\theta$ that determine the position of one Cartesian rectangular coordinate system $0xyz$ relative to another one $0x'y'z'$ with the same origin and orientation. The Euler angles are regarded as the angles through which the former must be successively rotated about the axes of the latter so that in the end the two systems coincide (see Fig.).
Let $u$ be the axis coinciding with the line of intersection of the planes $0xy$ and $0x'y'$, oriented so that the three lines $0z$, $0z'$ and $u$ form a right-handed triple. Then $\psi$ is the angle between $0x$ and $u$, measured in the plane $0xy$ from $0x$ in the direction of the shortest rotation of $0x$ to $0y$, $\theta$ is the angle between $0z$ and $0z'$ not exceeding $\pi$, and $\phi$ is in the direction of the shortest rotation of $0x'$ to $0y'$. The coordinates $x,y,z$, and $x',y',z'$ are connected by the relations
These angles were introduced by L. Euler (1748).
|[a1]||L.D. Landau, E.M. Lifshits, "Mechanics" , Pergamon (1965) (Translated from Russian)|
|[a2]||G. Gallavotti, "The elements of mechanics" , Springer (1983)|
|[a3]||H. Goldstein, "Classical mechanics" , Addison-Wesley (1959)|
Euler angles. Encyclopedia of Mathematics. URL: http://www.encyclopediaofmath.org/index.php?title=Euler_angles&oldid=34483