1. The problem statement, all variables and given/known data Hello! I've been trying to prove a problem. I attach the problem. I refer to the book " Advanced calculus" written by watson fulks. You can find the below information in p. 405~p.417 I wanna prove C Exercise problem number 2. 2. Relevant equations 3. The attempt at a solution I could prove it when two parametrizations of a curve are bijective. But, I don't have any idea to access how to prove it in general. I even don't know whether the statement in C Exercise 2 is true or not... Is the statement true?? Then, could you give me a hint??