# Trig identities:(

Sin4A - cos4A = sin2A - cos2A

Can i just square root the left side??:O

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1. I don't think it is an identity.
let A=90 deg
sin(360)-cos(360)=0-1

sin(180)-cos(180)=0+1

The sides are not equal.

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bobpursley
2. ?? Im sorry i don't understand what u did but im sure that this is an identity we have to prove that the left side equals the right side:)

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