Math, asked by Reyansh05, 1 year ago

sinx +sin3x +sin5x + sin7x = 4cosx cos 2x sin 4x .prove that

Answers

Answered by sprao534
5
Please see the attachment
Attachments:
Answered by BrainlyMOSAD
23
LHS


= sinx + sin3x + sin5x + sin7x


= (sin7x+ sinx )+ (sin5x + sin3x)


 = \: 2sin \frac{7x + x}{2} \: \: cos \frac{7x - x}{2} \: + \frac{5x + 3x}{ \: 2} \: cos\frac{5x - 3x}{ \: 2}

= 2sin 4x cos3x + 2sin 4x cosx


= 2sin4x [ cos3x + cosx ]


 = 2sin4x \: \: 2cosx \: \frac{3x + x}{2} \: cos \: \frac{3x - x}{2}


= 4sin 4x . cos 2x . cosx


=4cosx . cos2x . sin4x


be create a brainly

regards:- rishi arya
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