A projectile is fired up an incline (incline angle ) with an initial speed vi at an angle i with respect to the horizontal (i

A projectile is fired up an incline (incline angle θ) with an initial speed vi at an angle θi with respect to the horizontal (θi > θ), as shown in Figure P4.50.
(a) Show that the projectile travels a distance d up the incline, where
(b) For what value of i is d a maximum, and what is that maximum value?