2sin^2x + 2sinx - 1= 0
2sin^2x + 2sinx =1
2sin^2x + 2sinx = sin^2x +cos^2x
2(1-cos^2x) + 2sinx =sin^2x +cos^2x
2-2cos^2x + 2sinx = sin^2x +cos^2x
2+2sinx = sin^2x + 3cos^2x
3+2sinx = sin^2x + 3cos^2x +1
3-3cos^2x=sin^2x - 2sinx +1
3(1-cos^2x)= (1-sinx)^2
3*sin^2x = (1-sinx)^2
√3sinx=1-sinx
√3sinx + sinx=1
sinx(√3+1)=1
sinx=1/√3+1