An automated weapon located at the point O on the horizontal ground identified an enemy’s aircraft flying horizontally with the velocity U and the same instant the coordinate of the aircraft (d ,

An automated weapon located at the point O on the horizontal ground identified an enemy’s  

aircraft flying horizontally with the velocity U and the same instant the coordinate of the aircraft  

(d , h ) corresponding to the point O. Instantly the weapon projects a bullet in the angle to the  

horizontal and it colliedes the aircraft when it comes to its maximum height h .Show that  

d= 2h (cosec + cot )