Finding the Angle of Rotation

Key Questions

  • xy term in the equation of a conic section indicates, there is a rotation of axes

  • Answer:

    Use a formula and solve for angle of rotation = theta

    Explanation:

    For the formulas I use, we must put the equation in the form:

    Ax^2 +Bxy+Cy^2 +Dx + Ey +F =0

    Use cot2theta = (A-C)/B or tan2theta = B/(A-C).

    Solve for theta.

    (The D, E, " and " F are not used in the formulas.)

    Your textbook/teacher may prefer a different form, which would lead to different formulas.

    Note/Example:
    If A = C, then cot2theta = 0, so theta = pi/4

Questions