$$2 \sin ^ { 2 } A + 3 \sin A - 2 = 0$$
$A=2\pi n_{1}+\frac{\pi }{6}\text{, }n_{1}\in \mathrm{Z}$
$A=2\pi n_{1}+\frac{5\pi }{6}\text{, }n_{1}\in \mathrm{Z}$
