 Euler's rotation theorem

Euler's rotation theorem states that any rotation of a rigid body in three-dimensional space can be represented as a single rotation about a specific axis. This means that for any arbitrary rotation, it is possible to find an axis in space such that the body can be considered to have rotated around this axis by a specific angle. More formally, the theorem states that given any rotation defined by a rigid body transformation, there exists a unique axis of rotation and a corresponding angle of rotation about that axis.