[tex]sin^{2}\alpha =\frac{16}{25}\Rightarrow cos^{2}\alpha =1-sin^{2}\alpha =\frac{9}{25}[/tex]
vì [tex]\frac{\Pi }{2}< \alpha < \Pi[/tex] nên cos <0
suy ra
[tex]cos\alpha =\frac{-3}{5}; tan\alpha =\frac{sin\alpha }{cos\alpha }=\frac{-4}{3} ; cot\alpha =\frac{1}{tan\alpha }=\frac{-3}{4}[/tex]
auto qua màn nhé bạn

)