Find the final speed of a skier if he lands 145m down a 20 degree slope?

[woopycushion]

Homework Statement

A skier leaves the starting gate at the top of a ski jump with an initial speed of 4.00 m/s. The starting position is 120m higher than the end of the ramp, which is 3.00m above the snow. Find the final speed of the skier if he lands 145m down the 20 degree slope. Assume there is no friction on the ramp, but air resistance causes a 50% loss in the final kinetic energy. The GPS reading of the elevation of the skier is 4212m at the top of the jump and 4039m at the landing point.

Homework Equations

U(x)=mgy
KE = (1/2)mvf^2 - (1/2)mvi(2)
vi = 4.00 m/s

The Attempt at a Solution

 

[Simon Bridge]

That's a good start - a sketch of what happens will also help you.
If you make an attempt at the solution I will be in a position to help you ;)