Question
[(sinx – 2sin 3 x)/(2cos 3 x –
cosx)] 2  + 1, x ≠45 o , is equal to:Solution
[(sinx – 2sin 3 x)/(2cos 3 x – cosx)] 2  + 1
= [sinx(1 – 2sin 2 x)/cosx(2cos 2 x – 1)] 2  + 1 = [tanx(cos2x)/(cos2x)] 2  + 1 = tan 2 x + 1
= sec 2 x
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