Question

a projectile is fired with an initial velocity of 800 ft/s at a target of 12000 ft downrange and at an elevation of 3000 ft above the ground, neglecting air resistance, determine the angle(s) that can be used to reach the target.

Answer 1

This looks like a physics question. I never heard of "university of saint la salle" as a School Subject.

Answer 2

well, you know the equation of the altitude of the trajectory is

y = x tanθ - g/(2 v^2 cos^2θ) x^2
So, just solve for θ in

12000tanθ - 9.8/(2(800cosθ)^2) = 3000
θ = 14°

Better check my math.