ko..soo the 3 identities v use are..
sin2x = 2sinx cos x
cos2x = cos2x - sin2x
sin2x + cos2x = 1
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k now first...simplify the LHS
therefore....RHs => cos2x + 6sinx cosx + 9sin2x
now the LHS => 5 - 4cos2x + 3sin2x
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lets break the LHS into 3 parts => 5 ; -4cos2x ; 3sin2x
now 5 = 5sin2x + 5cos2x
...-4cos2x = -4cos2x + 4sin2x
... 3sin2x = 6sinx cos x
(check the first 2 identities)
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so LHS => 5sin2x + 5cos2x -4cos2x + 4sin2x + 6sinx cos x
now cancel them and u get the RHS