Math Is Fun Forum

An aircraft flies at a constant height H and constant velocity V. When the aircraft has flown directly over a gun on the ground a shot is fired from the gun which points at the aircraft at an angle of elevation Ѳ. If the initial velocity of the bullet is KVsecѲ [k >1], and Ѳ =tan inverse[ 1/V√gh/(k-1) ], show that the bullet hits the aircraft directly.

Please if any one can answer me this question I appreciate it a lot.