I want to make this completely clear:
After doing VCE chemistry, I entered into a science degree where I got a double major in Chemistry. All you need to understand, is that means I did a lot of chemistry. This included second year and third year electrochemistry. I then went on to do honours in physical and synthetic chemistry. I am now doing a PhD in physical chemistry, in which I look at equations all the time. Not just simple equations, either - I constantly use maths involving integrals, differentials, exponents, logarithms, etc., and have even had to learn how to code and use maths to explain my chemistry.
Not only have I never heard of the Cottrel equation, but looking at it made my head hurt. You definitely don't need to know it for VCE.