Topic summary
Centre of rotation
Extracted from the Wikipedia article 2D rotation.
In geometry and physics, a 2D rotation is a rotation in two dimensions, commonly on the Euclidean plane. It leaves unchanged a single point, the centre of rotation, often assumed at the origin of the coordinate system. The amount of rotation is represented by the angle of rotation, expressed in units of measurement such as degrees or radians; a signed angle allows for two different senses of rotation: clockwise or anti-clockwise. It corresponds to the 2D special orthogonal group or SO(2).