Let's say a rotation of the desired form abou theOriginally Posted byMathman24originis of the form where A is a matrix and x and y are 2-vectors. You'll have to determine the matrix A - your solution isn't correct since it doesn't pay attention to the 90 degrees. Such a rotation is linear.

Suppose now you want to rotate about a different point, say . Set . This is the displacement of the point x from .

Then is the rotated position vector, relative to the point , and therefore is the formula for the rotation about .