Explain briefly please......Q 9
Explain briefly please......Q 9 EXAMPLE 9 If = sin x cos x and b = cos x sin x, then (a) a—b > 0 fo x e (0, It/4) (b) a —b < 0 for xe (0, Tt/4) (c) a +b < 0 for xe (O, It/ 2) (d) a +b < 0 for xe (0, It/4) Ans. (a) SOLUTION We have, a—b = sinxcosx (cos x —sin x) a—b>0for0 O for O < < O < x < ¯ 2

Dear student

a=sinxcos3xb=cosxsin3xConsider, a-b=sinxcos3x-cosxsin3x=sinx cosx cos2x-sin2x=sinx cosx cos2x     as cos2A=cos2A-sin2A=2sinx cosx cos2x2=sin2x cos2x2  as sin2A=2sinAcosA=2 sin2x cos2x4=sin4x4       as sin2A=2sinAcosA
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