I don't see an equation with cotangent but I can graph [tex]y=-\tan\left(\frac{\pi x}4\right)[/tex].
The input of the tangent function is multiplied by [tex]\frac{\pi}4[/tex]. Normally, the tangent function has asymptotes at [tex]x=\pm\frac{\pi}2,\pm\frac{3\pi}2,\pm\frac{5\pi}2\ldots[/tex]. Instead, each of these aymptotes will be divided by [tex]\frac{\pi}4[/tex] (when the input is multiplied, the known x values are divided). That means the new function has asymptotes at [tex]x=\pm2,\pm6,\pm10\ldots[/tex]. The new function's period is 4.
Normally, the slope of the tangent function is 1 at 0, and whenever it crosses the x axis. Your function is negative, so instead of drawing from negative infinity to infinity with a positive slope when it intersects 0, draw from positive infinity to negative infinity with a negative slope when it intersects 0.
