use the formula X=x cos theta - y sin theta and Y= x sin theta + y cos theta.then after simplifying the equation after putting the values of the above X and Y in the given equation,check the coefficient of x and y.both of them are equal to zero.solve the 2 equations to get the value of theta.rate me if useful.
1) use the formula X=x cos theta - y sin theta and Y= x sin theta + y cos theta. ( Here u rotate the axes).
2)after simplifying the equation after putting the values of the above X and Y in the given equation,check the coefficient of xy , since it is not there in the final equation , equate it to 0 . Thus u'll get theta.
3) now substitute theta in the equation.
4) now remove the coefficients of x and y ( not x2 and y2 ) . use X= x+h, Y=y+k and the method of completing the squares.
Here u r changing the origin. Now u get the answer.