SOLUTION: verify trigonometric equation as identity sin^4x-cos^4x=2sin^2x-1

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Question 561913: verify trigonometric equation as identity
sin^4x-cos^4x=2sin^2x-1
Answer by Edwin McCravy(20060)   (Show Source): You can put this solution on YOUR website!
 -  ≟  - 1

Factor the left side:

[ - ][ + ]

Use the identity  to replace the 2nd factor by 1

[ - ][1]

 - 

Use the identity  to replace the 2nd term

 - ()

 -  + 

Combine the sinē terms:

 - 

Edwin
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