2cos^2θ−3sinθ=0
2(1-sin^2theta)−3sinθ=0 because cos^2θ+sin^2theta=1
2-2sin^2theta−3sinθ=0
2sin^2theta+3sinθ-2=0
sinθ=(-3+-sqrt(3^2-4*2*(-2)))/(2*2)
sinθ=(-3+-sqrt(9+16))/4
sinθ=(-3+-sqrt(25))/4=(-3+-5)/4
sin theta=-8/4 or sin theta= 2/4
sin theta=-2 or sin theta= 1/2
theta notin RR or sin theta= 1/2
theta= 60^o or theta= (-60^o +360^o)
theta= 60^o or theta= 300^o