Q40 of 51 Page 54

Prove that: tan x + tan 2x + tan 3x = tan x tan 2x tan 3x

Formula :



Put 3 x = x + 2 x


Taking tan on both the sides we get,


tan (3 x ) = tan (x + 2 x)


Applying the formula we get,



Cross Multiplying we get,


Tan 3 x – tan x tan 2x tan 3x = tan x + tan 2x


Tan x + tan 2x + tan 3x = tan x tan 2x tan 3x


Hence, Proved.


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