Question

Pls Pls Pls help... I have been stuck for a while!!!
Prove
tan3x = (3tanx - tan^3 x) / ( 1 - 3tan^2 x)

using sin3x/ cos3x = tan3x
sin3x = 3sinx - 4sin^3 x
cos3x = 4cos^3 x - 3cosx

Answer 1

Have you tried using\[\tan(3x)=\tan(2x+x)\]
Then
\[\tan(A+B)=\frac{tanA+tanB}{1-tanAtanB}\]

Answer 2

the question asked to solve it using tan3x = sin3x / cos3x :/