how do i prove (sin^4 x)-(cos^4 x)= (2sin^2x)-1
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Originally Posted by somanyquestions how do i prove (sin^4 x)-(cos^4 x)= (2sin^2x)-1 Expand....
Originally Posted by pickslides Expand.... ?? expand?
Originally Posted by Stroodle i have no idea what that means but this is what i did: sin4 x -(1- 2sin^2 x + sin4 x) sin4 x - 1+ 2sin^2 x - sin4 x sin4 x's cancel out -1+2sin^2 x = 2sin^2 x-1
Originally Posted by somanyquestions ?? expand? finish...
That works too
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