Transformations article expanded and split into two parts

I have added a new section to the Transformations article on transforming the equation of a curve from first principles, because while writing questions, it became clear this new section would be highly useful. Rather than changing the input or output of a function, this method tracks what happens to an arbitrary point $(p,q)$ and recovers the equation from its image. It handles cases the usual approach struggles with — in particular curves that are not written in the form $y=f(x)$ at all.

The article was already too long before this, and now it's definitely too long! So I decided to split it into two sections. Sorry the other topics will have to wait, as I need to do this right! 🙂

• Part A — Core transformations and equations of curves: the vertical and horizontal transformations, the order in which they combine, reflections in $y=b$ and $x=a$, and the new first-principles method.
• Part B — Modulus transformations, point mapping and rotations: the modulus transformations $|f(x)|$ and $f(|x|)$, a shortcut for finding corresponding points directly, and the bonus section on rotating a curve through $90^\circ$.

I might add to this news update later today when I have completed the practice and topic tests, which I am writing right now!