1. The problem statement, all variables and given/known data 1. Find the maximum angle of projection of a projectile such that its position vector from the origin to the subsequent position of the projectile is always increasing. 2. Relevant equations 3. The attempt at a solution x(t)=v*cos(A)t, y(t)=v*sin(A)t-(1/2)gt^2. v is the initial velocity, A is the angle from the horizontal. then x^2 +y^2 =k^2 We know that k^2 should always be increasing then we would differentiate it w.r.t to time and put it ≥ 0. But the problem is that i am getting two times for it. now what to do..?