Question

Given that 2sin^2 theta + sin theta -1 = 0, find the two values for sin theta.

Answer 1

2sin^2 θ + sin θ - 1 = 0
2sin^2 θ + 2sin θ - sin θ - 1 = 0
2sin θ(sin θ + 1) - 1(sin θ + 1) = 0
(2sin θ - 1)(sin θ + 1) = 0
2sin θ - 1 = 0 or sin θ + 1 = 0
sin θ = 1/2 or sin θ = -1

The two values of sin θ are 1/2 and -1