Trigonometry- Double Angle Trigonometric Equations tan(3x)=((tan x(3-tan^2x))/(1-3 tan^2x)) I'm just having a hard time seeing where the double angle formula fits in with verifying this equation.

Alice Chen

Alice Chen

Answered question

2022-11-05

Trigonometry- Double Angle Trigonometric Equations
tan ( 3 x ) = ( ( tan x ( 3 tan 2 x ) ) / ( 1 3 tan 2 x ) )
I'm just having a hard time seeing where the double angle formula fits in with verifying this equation.

Answer & Explanation

Milton Gilmore

Milton Gilmore

Beginner2022-11-06Added 20 answers

Using a Adicional formula:
tan ( x + y ) = tan x + tan y 1 tan x tan y ,
we have:
tan ( 2 x + x ) = tan 2 x + tan x 1 tan 2 x tan x = tan ( x + x ) + tan x 1 tan ( x + x ) tan x = tan x + tan x 1 tan x tan x + tan x 1 tan x + tan x 1 tan x tan x tan x
= tan x + 2 tan x 1 tan 2 x 1 tan x 2 tan x 1 tan 2 x = tan x tan 3 x + 2 tan x 1 tan 2 x 1 tan 2 x 2 tan 2 x 1 tan 2 x
= tan x tan 3 x + 2 tan x 1 tan 2 x 2 tan 2 x = 3 tan x tan 3 x 1 3 tan 2 x = tan x ( 3 tan 2 x ) 1 3 tan 2 x
paratusojitos0yx

paratusojitos0yx

Beginner2022-11-07Added 2 answers

tan ( 3 x ) = sin ( 2 x + x ) cos ( 2 x + x ) = sin ( 2 x ) cos x + sin x cos ( 2 x ) cos ( 2 x ) cos x sin ( 2 x ) sin x = 3 sin x 4 sin 3 x 3 cos x + 4 cos 3 x = ( tan x ) 3 4 sin 2 x 3 + 4 cos 2 x

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