An charged particle with a mass m and charge q initiate from a point P on y axis with velocity v0, and the angle between v0 and y axis is theta. By applying a circular edged uniform magnetic field B perpendicular to xy plane on the path of the particle, the particle reach a point Q on x axis with a velocity perpendicular to x axis. Where m, q, B, v0 and theta are positive quantities with appropriate units. What is the minimal possible area of the magnetic field applied