1. The problem statement, all variables and given/known data Partial derivative of R = vt cos x with respect to t 2. Relevant equations NA 3. The attempt at a solution Keeping the other variables constant, I get 'v cos x'. (t is 1) I just want to check this, because it's part of a larger problem and I feel my answer is way off because of this function. I'm a bit rusty on my calculus, it's been ... 13 years since I did it in highschool! Also, if I calculate the partial derivative with respect to x, I get '-vt sin x'?