Prove that =
Cos 7x + cos 5x
sin 7x + sin 5x
=cot x
Answers
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Step-by-step explanation:
LHS=(co7x+cos5x)/(sin7x+sin5x)
=2cos[(7x+5x)/2]cos[(5x-7x)/2]/{sin[(7x+5x/2)]cos[(7x-5x)/2]}
=(cos6xcosx)/(sin6xcosx)
=cosx/sinx
=cotx
LHS=RHS
hence proved
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