I have been stuck on this for a while....
A projectile's launch speed is five times it speed at maximum height. Find the launch angle.
Anybody have any clue how to do this?
(at maximum height), since this is the parabolic path of a projectile. So you have an unknwn velocity at maximum height, , an, unknown initial velocity, , and an unknown angle , which you need to find. I'd say there isn't enough information to find it. if you are assuming gravity of , and have the final velocity, the launch and impact heights, then you could plug in the values for x and y, and solve simultaneous equations using the equations of motion.