Question

cos7x+cos5x/sin7x+sin5x=cotx​

Answer 1

Answer:

Here, we will use the following formulas:

sinA−sinB=2sin(A−B2)cos(A+B2)

cosA+cosB=2cos(A−B2)cos(A+B2)

L.H.S.=cos7x+cos5xsin7x−sin5x

=2cos(7x+5x2)cos(7x−5x2)2cos(7x+5x2)sin(7x−5x2)

=cos(x)sin(x)=cotx=R.H.S.

Step-by-step explanation:

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