ezzy - thats the way to do it.
physics formulas suck compared to doing it the maths way. if you learn the maths way, physics will be faster and you dont need to remember any formulas or look at the formula sheet even.
Trying to do maths projectiles with physics formulas is stupid, since they will most likely ask for your derivations anyway.
btw ezzy - the two basic equations are
X-acceleration = 0
Y-acceleration = -g
Just keep integrating to get velocities and displacements.
The main eqn you will use for 3U (Cartesian Eqn of Motion) is when you solve y-displacement for time = x/(Vcos@)