4meisu
Given that 2sin^2 θ + sinθ  1 = 0, find the two values for sin θ



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

lgbasallote
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imagine \(\sin \theta = x\)
so this thingy will become 2x^2 + x  1 = 0
do you know how to solve for x there?

ashna
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so much can you understand ?

ashna
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@4meisu ?

4meisu
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No I do not know how to solve for x.. What's next?

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

4meisu
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yes

4meisu
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sinθ = 1/2 and sinθ = 1 ?

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

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

4meisu
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Okay thank you

ashna
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:)

4meisu
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The question is asking for only two values for theta though, which one would we choose?