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Skynt,

You are almost there.

work little more on dominator then it will become

( sin^2x - cos^2x ) / ( sin x - cos x )

and then

[ (sin x + cos x) ( sin x - cos x) ] / ( sin x - cos x)

and you start to cancel ( sin x - cos x ) at numinator and dominator. the only thing left is ( sin x + cos x )