Bài 1:
\(cosx=\sqrt{1-\dfrac{1}{9}}=\dfrac{2\sqrt{2}}{3}\)
\(tanx=\dfrac{1}{2\sqrt{2}}=\dfrac{\sqrt{2}}{4}\)
\(cotx=2\sqrt{2}\)
Bài 2 : tan x = 3 \(\Rightarrow cotx=\dfrac{1}{3}\)
\(1+tan^2x=\dfrac{1}{cos^2x}\Rightarrow1+9=\dfrac{1}{cos^2x}\) \(\Rightarrow cosx=\pm\dfrac{1}{\sqrt{10}}\)
cos x = \(\pm\dfrac{1}{\sqrt{10}}\Rightarrow sinx=\pm\dfrac{3}{\sqrt{10}}\)