I need help on this question

A projectile fired into the first quadrant from the origin of a coordinate system will pass through the 2x point (x,y) at time t according to the relationship cot 0 = - where 0 is the angle of elevation 2y + gt2 of the launcher and g is the acceleration due to gravity (32.2 feet/second-). An artilleryman is firing at an enemy bunker located 2750 feet up the side of a hill that is 6000 feet away. He fires a round, and exactly 2.85 seconds later he scores a direct hit. . . . . . (a) What angle of elevation did he use? 0 = (Do not round until the final answer. Then round to one decimal place as needed.)