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February 1, 2015

February 1, 2015

Posted by **Joe** on Wednesday, July 13, 2011 at 4:03pm.

I'm not sure how to properly square the -1/sqrt10 and keep an exact answer other than decimal. Otherwise, my final answer is 1.632455533

- Pre-Calculus -
**bobpursley**, Wednesday, July 13, 2011 at 5:24pmif sintheta=-1/sqrt10, then

costheta= (10-1)/sqrt10= sqrt (9/10)

check those.

Then sin2theta= sintheta*costheta=-2/sqrt10*sqrt9/10

= sqrt9 /5=3/5=.6

cos2Theta=1-2sin^2 theta=1-2(1/10)=.8

check all that. I have no idea what you did.

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