Principle unit normal and curvature

[fsufreak78]

Need help with this one. The problem says Find the unit vector tangent to v=<sinx,2cosx> and K(curvature/Kappa) and the Principle unit normal N. The curvature and principle unit normal is whats giving me trouble.

 

[HallsofIvy]

Well, what have you done? Have you found the tangent vector to the curve? Do you know how to find the normal vector from that?