Question

Solve the equation 2sin^2θ -sinθ -1=0

Answer 1

notice is just a quadratic equation

Answer 2

Let sinθ=t and solve.

Answer 3

Let sin θ = x
2x2 - x - 1 = 0
Solve this quadratic equation to get 2 values of x and sinθ

Understood? :)

Answer 4

\(\bf 2sin^2(\theta) - sin(\theta) - 1=0 \quad ,\color{blue}{sin(\theta) = t},\quad \implies 2t^2-t-1=0\)

Answer 5

so would the answer just be -1/2 and 1?

Answer 6

Yes. :)
Find θ just like that.