$$\sin Q = \frac { 4 } { 7 }$$
$Q=2\pi n_{1}+\arcsin(\frac{4}{7})\text{, }n_{1}\in \mathrm{Z}$
$Q=2\pi n_{2}+\pi -\arcsin(\frac{4}{7})\text{, }n_{2}\in \mathrm{Z}$
