Biết tan = 4/3 .Tính sin, cos, cot Helpp

$\displaystyle  \begin{array}{{>{\displaystyle}l}}
tan\ x\ =\ \frac{4\ }{3\ } \ \\
tan\ x\ .\ cot\ x\ =\ 1\\
cot\ x\ =\ 1:\ \frac{4\ }{3\ } =\ \frac{3\ }{4\ }\\
sin^{2} \ x\ +\ cos^{2} \ x\ =\ 1\ \\
sin\ x\ =\ \sqrt{1\ -\ cos^{2} \ x\ }\\
tan\ x\ =\ \frac{sin\ x\ }{cos\ x\ } =\ \frac{\sqrt{1\ -\ cos^{2} \ x\ }}{cos\ x\ } =\ \frac{4\ }{3\ }\\
3.\ \sqrt{1\ -\ cos^{2} \ x\ } \ =\ 4\ cos\ x\ \\
9.\ \left( \ 1-\ cos^{2} \ x\ \right) \ =\ 16\ cos^{2} \ x\\
-25\ cos^{2} \ x\ =\ -9\ \\
cos^{2} \ x\ =\ \frac{9\ }{25\ }\\
cos\ x\ =\+- \frac{3\ }{5\ }\\
sin\ x\  =\ +-\frac{4\ }{5\ }
\end{array}$