Question

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

Answer 1

2sin² θ + sin θ - 1 = 0
(2sin θ - 1)(sin θ + 1) = 0

Answer 2

imagine \(\sin \theta = x\)
so this thingy will become 2x^2 + x - 1 = 0

do you know how to solve for x there?

Answer 3

so much can you understand ?

Answer 4

@4meisu ?

Answer 5

No I do not know how to solve for x.. What's next?

Answer 6

Now we can split that into two equations
2sin θ - 1 = 0
and
sin θ + 1 = 0
this much understood ?

Answer 7

yes

Answer 8

sinθ = 1/2 and sinθ = -1 ?

Answer 9

Solving the first one:
2sin θ - 1 = 0
sin θ = 1/2
θ = 30°, 150°

Answer 10

Second:
sin θ + 1 = 0
sin θ = -1
θ = 270°

Answer 11

Okay thank you

Answer 12

:)

Answer 13

The question is asking for only two values for theta though, which one would we choose?