Math, asked by nishukalra999, 5 hours ago

prove that
. sin (n + 1)x sin (n + 2)x + cos (n + 1)x cos (n + 2)x = cos x
(BT
(3т

Answers

Answered by adiwan2

2

the whole step by step proof is given in the picture

Attachments:

Answered by prajapatidhnj

0

Step-by-step explanation:

L.H.S = sin(nx+x).sin(nx+2x) + cos(nx+X).cos(nx+2x)

=cos(nx+X).cos(nx+2x) + sin(nx+x).sin(nx+2x)

=cos(nx+x-nx-2x)

=cos(-x)

=cos x

=R.H.S

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