Answer
$y=-cot(x-\frac{\pi}{2})$.
Work Step by Step
The function $y=-cot(x-\frac{\pi}{2})$ shifts the original $y=cot(x)$ to the right by $\frac{\pi}{2}$ and then reflects the result with respect to the x-axis and gives the graph in this case. Thus the answer is $y=-cot(x-\frac{\pi}{2})$.
