# Mathematica: What is happening?

• Mathematica

## Main Question or Discussion Point

Ok, I have either completely lost it (very likely) or Mathematica is being weird (much less likely). The finction D[f,x] is supposed to return the partial of f with respect to x, $\partial{f}/\partial{x}$.

So I have a function $V_\theta = (A/r^2 + B)\sin\theta$ where A and B are constants. So we should have $\partial{V_\theta}/\partial{\theta} = (A/r^2 + B)\cos\theta$.

But here is what mathematica is returning. What does that even mean? Why does it just say "sin" and not have the argument? Moreover, why does it not say cos ?!

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