2sinx + 1 = 0
2sinx+1=0
2sinx=-1
sinx=-1/2
x=(-1)^(k+1)(arcsin(-1/2)+(pik)
x=(-1)^(k+1)* (pi/6)+(pik)
2sin(x)+1=0
sin(x)=-1/2
x=(-1)^n*arcsin(-1/2)+pi*n
x=(-1)^n*7*pi/6+pi*n