- #1
theintarnets
- 64
- 0
Homework Statement
cosθ = sin2θ/2
Homework Equations
None.
The Attempt at a Solution
I really don't know what to do. I tried using the half and double angle identities and this is what I got:
cosθ = (1-cos2θ)/2
2cosθ = 1-cos2θ
2cosθ + cos2θ = 1
2cosθ + 2cos2θ -1 = 1
2(cosθ + cos2θ) = 2
cosθ + cos2θ = 1
cos2θ + cosθ - 1 = 0
I'm not sure if that can be factored, so I tried using the quadratic formula. I got (-1 ± √5)/2
What am I supposed to do now? I don't even know if I did this right. Someone pleeeaase help mee ):
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