Projectile Motion -- need urgent help :) If a projectile is fired from the origin of the coordinate system with an initial velocity v and in a direction making an angle alpha with the horizontal, calculate the time required for the projectile to cross a line passing thorugh the origin and making an angle beta less than alpha with the horizontal. I know that the position of the projectile is described by y=y0+v0(sin alpha)*t-4.9t^2. I let the line be y=ax. I also drew a triangle with Beta as the angle, y=ax as the opposite side, and x as the adjacent side. I'm assuming I want to find y in terms of Beta and then set this equal to y in my projectile motion equation...then solve for t??? Thanks in advance!!!