0

9. Значения выражений \ Тип 5


\(\DeclareMathOperator{\tg}{tg}\)\(\DeclareMathOperator{\ctg}{ctg}\)\(\DeclareMathOperator{\arctg}{arctg}\)\(\DeclareMathOperator{\arcctg}{arcctg}\)
Найдите \(\ctg\alpha\), если \(\cos\alpha=-\dfrac{4}{\sqrt{17}}\) и \(\alpha\in(\frac{\pi}{2};\pi)\).