Answer
$y = tan~(x-\frac{\pi}{2})$
We can see the graph below.
Work Step by Step
$y = tan~(x-\frac{\pi}{2})$
When $x = 0$, then $y = tan~(-\frac{\pi}{2})~~$ (which is undefined)
When $x = \frac{\pi}{4}$, then $y = tan~(-\frac{\pi}{4}) = -1$
When $x = \frac{\pi}{2}$, then $y = tan~0 = 0$
When $x = \frac{3\pi}{4}$, then $y = tan~\frac{\pi}{4} = 1$
When $x = \pi$, then $y = tan~\frac{\pi}{2}~~$ (which is undefined)
We can see the graph below.
