User:Blackbombchu/Sandbox/Definition:Origin Rotation

R2
In R2, an origin rotation is a function T from R2 to R2 such that
 * There exists real numbers a, b such that for all x, y ∈ R, T(x, y) = (ax - by, ay + bx)
 * C ∘ T = T-1 ∘ C