Calculus is quite new to me, so I think I'm starting from scratch and might be in over my head. Forgive my basic knowledge... When considering two variables, how does one know which one is the independent or dependent variable? For instance - The area A of a circle depends on the radius r of the circle. Okay, it clearly states that A is dependent on r. But can you not also say that r is dependent on A? If you have a bigger radius then you'll have a bigger area. But vice versa, if you have a bigger area than then don't you automatically get a bigger radius? Doesn't this mean that they can both be considered the dependent or independent variable depending on how you view the question? Thank you!