an aeroplane fly upward at 100m/s at an angle 50.when it reached altitude of 900m,a package is throw down.

calculate the distance along the groundfrom the point of released

Multiply the horizontal velocity component,

Vx = 100 cos50 = 64.28 m/s,
by the time required to fall to the ground, T. Get T by solving the equation:

100 sin50*T - 4.9 T^2 +900 = 0

Take the positive root of the two possible solutions