Ok, I know this post is not up to specs but the real problem with this is my trouble with calculus and derivatives (I'm actually worse at that than at English ;) ) in general. I only need help with this step of the homework (basic math help). This describes the movement of the point: x= 4*x0*cos (Angular velocity*time) y= x0*sin (2*angular velocity*time) Angular velocity is given as is x0. At first I just thought dx/dt = v, and went for it by using the rule (dsink*k/dx=k*cos(k*x)) got: Vx=-4x0*angular velocity* sin (angular velocity*t) Vy=x0*2*angular velocity*cos (2*angular velocity*t) I know this is wrong. Since I realised as soon as I wrote it that, angular velocity is v/r so d(v/r)/dt, trying to get throught that using the rule for d(f(x)/g(x))/dx it got quickly complicated since looking at the XY graph (I got something that looks like a 8) for movment leads me to belive r is not constant. Anyway the more basic problem is that I don't know how to solve sin (f(x)*x)/dx or the second one for cos :( I can solve d(f(x)*x)/dx and dsin(x)/dx (since both are covered by the simple equations) but putting them together confuses the heck out of me. You guys where very patient and helpful with my previous problem, I hope I can learn from you again. :) Again, thaks for taking the time to help a newbie with something (for you) this trivial. :) PS I hope angular velocity is the proper english word the derivative for what I mean is dAngle/dTime its related to velocity (v= r * angular velocity).