SOLUTION: For the problem: Find all solutions to 2cos^2(theta) -1=0 I need to find all solutions I would rearrange to get cos2(theta)=1/2 why doesn't it go from cos2(theta) to 1-sin^

Question 964566: For the problem:
Find all solutions to
2cos^2(theta) -1=0
I need to find all solutions
I would rearrange to get cos2(theta)=1/2
why doesn't it go from cos2(theta) to 1-sin^2(theta)=1/2 since of the identity for cos(2(theta))?
I don't understand how it only becomes cos2(theta)=1/2 to become pi/6? what about the other identity? and what does 2(theta) mean exactly? why is the answer pi/6?
Please help
Thank you

Answer by Fombitz(32388) (Show Source): You can put this solution on YOUR website!
You should get the same answer either way since it is an identity.

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Not sure where comes into it?

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