Answers

2015-09-09T15:52:10+05:30
Split sin6 nd cos6 into (sin2)3+(cos2)3= use identity a3+b3 = (a+b)(a2+b2-ab) here a=sin2 b=Cos2 put this in identity u will get (sin2+cos2)((sin2)2+(cos2)2-sin2 cos2 )= (1)(sin4+cos4-sin2cos2) then add nd subtract 2sin2cos2= sin4+ cos4 -2sin2cos2+2sin2cos2 - sin2cos2 = (sin2+ cos2)2-3 sin2 cos2= 1-3sin2 cos2
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if this is not understood thn u shd go for RD sharma