# Math

(sinx - cosx)(sinx + cosx) = 2sin^2x -1

I need some tips on trigonometric identities. Why shouldn't I just turn (sinx + cosx) into 1 and would it still have the same identity?

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1. I'm a little confused. Is the right equal to 2sin to the power of 2x-1?

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2. Very simple
LS = sin^2 x - cos^2 x
= sin^2x - (1-sin^2 x)
= 2sin^2 x - 1
= RS

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