Figures that the only problem I have trouble with is the one the book considers to be "easy": 1. The problem statement, all variables and given/known data The speed of a projectile when it reaches its maximum height is one half its speed when it is at half its maximum height. What is the initial projection angle of the projectile? 2. Relevant equations h= (vi^2 sin^2 theta)/2g 3. The attempt at a solution Complete brain fart--I don't even know where to start, beyond trying to divide h/2, which would be (vi^2 sin^2 theta)/4g, correct? That's about as far as I got. I just keep miring myself the further into it I go.