tanA .tan 3A

how can we prove that (1+tan3A)/(1-tan3A) = { (1+tanA)/(1-tanA) }³??

2 Answers

Can this be proved take A=60Â°

it doesnt come out equal

u know that
tan2A=2tanA/1-tan²A

so
tan (2A+A)=2tanA/1-tan²A + tanA
-----------------------------------
1-2tan²A/1-tan²A

u get
tan3A=3tanA-tan³A
-------------------
1-3tan²A

now u can confirm that subash is correct[1]

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