SOLUTION: Prove the formula tan3@ = 3tan@ - tan^3@ / 1 - 3tan^2@. Hence solve the equation tan3@ = 0 If 0≤@≤360

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Question 1202935: Prove the formula tan3@ = 3tan@ - tan^3@ / 1 - 3tan^2@.
Hence solve the equation tan3@ = 0
If 0≤@≤360

Answer by math_tutor2020(3817)   (Show Source): You can put this solution on YOUR website!

One of the many trig identities is

Let's plug in A = x and B = x






this will be useful in substitution steps later on.


Go back to


Let's plug in
A = x
B = 2x
to get the following






This is one large fraction with
numerator = tan(x)+tan(2x)
denominator = 1-tan(x)*tan(2x)

In other words,

where

and


Let's apply a substitution in the numerator












Apply that same substitution with the denominator.













------------------------------------

Recall that this identity

is of the form

where

and


but we found these equivalent forms

and


The 2nd versions of P and Q involve the denominator .
Those expressions cancel when dividing.

Therefore,


------------------------------------

For the next part of the problem, here are a few hints:








I'll let you take over from here.

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