An arbitrary rotation may be described by only three parameters.
Euler's Rotation Theorem
See also
Euler Angles, Euler Parameters, Rotation MatrixExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Euler's Rotation Theorem." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/EulersRotationTheorem.html