Answers

2016-04-25T12:06:00+05:30
2cos[5A+3A/2]cos[5A-3A/2]+2cos[15A+7A/2]cos[15A-7A/2]
=2cos4AcosA+2cos11Acos4A
=2cos4A[cosA+cos11A]
=2cos4A[2cos[11A+A/2]Cos[11A-A/2]
=2cos4A2cos5Acos6A
=4cos4Acos5Acos6A
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