Question

Prove that tan4x=(4tanx-tan^3x)/(1-6tan^2 x+tan^4 x)
*note: the exponents are just numbers. there are no variables in the exponents.

Answer 1

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Answer 2

we know tan2A= 2tanA / 1-tan2A

using this formula,

tan4x = tan2.(2x)

=2tan2x / 1-tan22x

= 2(2tanx/1-tan2x) / 1-(2tanx/{1-tan2x}2)

simplify to get. , 4tanx(1-tan2x) / 1-6tan2x+tan4x.