A student launches a ball from a cliff that is at height of 20 meters.
He thros the ball at an angle of 45 degrees with an initial velocity
of 12 m/s
Note: the altitude of the ball(cliff) is 20 meters when it is launched and
then it does NOT return to 20 meters, but instead hits the water
below. i.e The ball does not return to the same altitude as it
started.
I need to know
a) the range of the ball 
b) the final velocity of the ball in the y direction right before it
hits the ground

thank you!