use an algebraic method.

this is pretty simple but i can't figure it out.

i just need help working out the question.

the question is: 2sinθ-1=cscθ

the answers are 90°, 210°, 330°.

2sinθ-1= 1/sinθ

(2sinθ-1)*sinθ= (1/sinθ)*sinθ

2sin^2θ-sinθ= 1

sinθ(2sinθ-1)= 1

sinθ=1

θ=90°

2siθ°-1=1

2sinθ=2

sinθ=1

.... i can't get the answers 210° and 330°, which would make sinθ= -1/2