[tex]\bf cot(u)=4\qquad \pi \ \textless \ u\ \textless \ \frac{3\pi }{2}\implies cot=\cfrac{-4}{-1}\cfrac{\leftarrow adjacent}{\leftarrow opposite}
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hypotenuse\implies \sqrt{(-4)^2+(-1)^2}\implies \sqrt{17}
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cos(\theta )=\cfrac{-4}{\sqrt{17}}\implies \cfrac{-4\sqrt{17}}{17}\\\\
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[/tex]
[tex]\bf sin\left( \frac{u}{2} \right)=\pm\sqrt{\cfrac{1+\frac{4\sqrt{17}}{17}}{2}}\implies \pm\sqrt{\cfrac{\frac{17+4\sqrt{17}}{17}}{2}}\implies \boxed{\pm\sqrt{\cfrac{17+4\sqrt{17}}{34}}}
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cos\left( \frac{u}{2} \right)=\pm\sqrt{\cfrac{1-\frac{4\sqrt{17}}{17}}{2}}\implies \pm\sqrt{\cfrac{\frac{17-4\sqrt{17}}{17}}{2}}\implies \boxed{\pm\sqrt{\cfrac{17-4\sqrt{17}}{34}}}[/tex]
[tex]\bf tan\left( \frac{u}{2} \right)=\pm\sqrt{\cfrac{\frac{17+4\sqrt{17}}{34}}{\frac{17-4\sqrt{17}}{34}}}\implies \boxed{\pm\sqrt{\cfrac{17+4\sqrt{17}}{17-4\sqrt{17}}}}[/tex]
