SOLUTION: I have to solve this function: f(-€/4)= cos2x
*let €= pi
So far I have gotten this far:
f(-€/4)= cos^2(-€/4) - sin^2(-€/4)
I figured that out using the double angle identit
Algebra.Com
Question 770544: I have to solve this function: f(-€/4)= cos2x
*let €= pi
So far I have gotten this far:
f(-€/4)= cos^2(-€/4) - sin^2(-€/4)
I figured that out using the double angle identity. Now, I need to simplify it but I can't remember how to solve it without using a calculator. I am supposed to use only the unit circle and trig identities.
Answer by solver91311(24713) (Show Source): You can put this solution on YOUR website!
What you have so far is just right. Now all you need are numbers to plug in for )
and )
Wikipedia Unit Circle
is in QIV, where 
and 
.
John
Egw to Beta kai to Sigma
My calculator said it, I believe it, that settles it
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