About Matrices Transformation (Rotation)

Let the original coordinate of point P be (x,y). And this point makes an angle A with the x-axis. And its distance from the origin = r. Therefore,
tanA = y/x, x=rcosA and y=rsinA.
Let P rotates anticlockwise about the origin for B degree and denotes as Q(X,Y). Therefore, point Q makes an angle (A+B) with the x-axis. Therefore,
X=rcos(A+B) and Y=rsin(A+B).
That is X = rcosAcosB - rsinAsinB = xcosB - ysinB. Similarly,
Y= rsin(A+B) = rsinAcosB + rcosAsinB = ycosB + xsinB.
Arranging in matrix form:
X= xcosB - ysinB
Y= xsinB + ycosB That is
(X = ( cosB -sinB) (x
Y) = (sinB cosB) y)

I am not very sure about your question. Do you mean that you want to know where is origin? It is (0,0).

If you do rotation, you have to know the direction (i.e. clockwise or anticlockwise) and also the degree. Now you have the direction (anticlockwise) but what about the degree? 90, 180, 270, 360?