How do you write the expression $(tan2x+tanx)/(1-tan2xtanx)$ as the sine, cosine, or tangent of an angle?

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Answer 1 · 2017-03-02T09:45:50

$tan3x=sin(3x)/cos(3x).$

Recall the Identity :

$tan(A+B)=(tanA+tanB)/(1-tanAtanB).$

With $A=2x, and, B=x$ , it follows that,

$"The Exp.="tan(2x+x)=tan3x=sin(3x)/cos(3x).$

How do you write the expression (tan2x+tanx)/(1-tan2xtanx)(tan2x+tanx)/(1-tan2xtanx) as the sine, cosine, or tangent of an angle?