
Projectile Motion
A ball is thrown with initial velocity 20 m/s at an angle of elevation of arctan (4/3). Suppose that the ball is thrown up a road inclined at arctan(1/5) to the horizontal. Show that the ball si about 9 m above the road when it reaches its greatest height and the time of flight is 2.72 seconds, and find, correct to the nearest tenth of a metre, the distance the ball has been thrown up the road.
I've already found out from previous parts that:
* the parabolic path of the ball has parametric equationx x=12t and y=16t5t^2
* the horizontal range of the ball is 38.4 m
* the greatest height is 12.8 m

Consider an inclined plane of inclination α. Let a projectile be fired making an angle θ along the horizontal. Call axis along the inclined plane to be xaxis. Thus the velocity makes an angle (θ  α) along xaxis.
The time of flight is given by
Maximum height above the road is