Problem 44936. Float like a cannonball

Given gravity on earth (g=9.81 [m/s/s]) find the distance s [m] by a cannonball propelled at a speed of u [m/s] from the origin at an angle theta [deg] measured from the horizontal. Assume no air resistance or bouncing. The altitude of the release of the cannon ball is 0 m and the travel should have the appropriate sign (i.e. behind the release point would be negative). Hint: Consider logical reasoning when the orientation of the firing vector would be into the ground!!