Math, asked by rubul98, 11 months ago

Sin A. Sin (A + B) = COS B-COS (2A+B)​

Answers

Answered by A1111
1

Dude !, check your LHS. It has to be 2sinA.sin(A + B)

Solving RHS :

= cosB - cos(2A + B)

= cosB - cos2A.cosB + sin2A.sinB

= cosB(1 - cos2A) + sin2A.sinB

= cosB.(2sin²A) + 2sinA.cosA.sinB

= 2sinA(sinA.cosB + cosA.sinB)

= 2sinA.sin(A + B) = LHS

Hope it'll help you.....

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