\(\sin \alpha = \sqrt {1 - {{\cos }^2}\alpha }\)\( = \sqrt {1 - \dfrac{9}{{16}}} = \dfrac{{\sqrt 7 }}{4}.\)
\(tg\alpha = \dfrac{{\sin \alpha }}{{{\rm{cos}}\alpha }} = \dfrac{{\sqrt 7 }}{3},\) \(\cot \alpha = \dfrac{1 }{ {tg\alpha }} = \dfrac{3}{{\sqrt 7 }} = \dfrac{{3\sqrt 7 }}{7}.\)
