Okay, So we are going over vectors in class, given Cartesian coordinates and convert them to polar, and vice-versa. So the question is that a skateboard rolls up a ramp shown in the image shown, at a initial speed of $85.0\:cm/s$ and slows down at $4.15\:m/s^2$. What is the initial velocity? Here is the image:
I honestly have no idea what to do, and my book doesn't seem to explain anything. I do know that $velocity\:=\:speed\:*\:direction$ and the book says (How do you find the angle from the diagram?) but I have no idea what to do.
So how do I find the initial velocity, and how do I find the acceleration (it's slowing down)? This can be in either polar or Cartesian coordinates.