Suppose a projectile is fired from a cannon with velocity and angle of elevation . The horizontal distance it travels (in feet) is given by the following. If , what angle (in radians) should be used to hit a target on the ground feet in front of the cannon? Do not round any intermediate computations, and round your answer(s) to the nearest hundredth of a radian. (If there is more than one answer, enter additional answers with the "or" button.)