Formula for a vertical cosine graph

Question

I was looking at Cosine and I thought it was cool, I was wondering what the formula for a horizontal version of it would look like.

A graph for Something like this :

Answer 1

To flip a function along the line $y=x$ then just switch $x$ and $y$. The graph of the picture above is a function of $y$:

$$x = f(y) = \cos y.$$

Answer 2

A simple one would be $x=cos(y)$.

Answer 3

The curve that you have drawn represents the multivaluated function $x(y)=\arccos(y)+2k\pi$ , on the system of axis : $y$ on the horizontal and $x$ on the vertical axis.

On the usual system of axis i.e.: $x$ on the horizontal and $y$ on the vertical axis the equation of the multivaluated function is : $y(x)=\arccos(x)+2k\pi$ where $k$ is any integer from $-\infty$ to $+\infty$