A skier is gliding along at 7.8m/s on a horizontal, fricionless snow. He suddenly starts down a 12.7degree incline. His speed at the bottom is 25.8m/s. What is the length of the incline?

Using trigonometry, work out the components of the gravitational force on the skier parallel to the slope.

Using this you can get an acceleration, and work out how many seconds it would take to get to 28.5 m/s.

From this you can then calculate the distance travelled.

If you need further help, feel free to ask, give it a go!