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Value of A for the equation: tan A + tan 2A+ tan 3A = tan A tan 2A tan 3A is
Question

Value of A for the equation:
tan A + tan 2A+ tan 3A = tan A tan 2A tan 3A is

A.

5π/6

B.

π/3, 2π/3

C.

2π/3 only

D.

π/3 only

Correct option is B

Given:

tan A + tan 2A + tan 3A = tan A tan 2A tan 3A

Solution:

tan A + tan 2A + tan 3A = tan A tan 2A tan 3A

=> tan A + tan 2A = -tan 3A + tan A tan 2A tan 3A 

=> tan A + tan 2A = -tan 3A (1 –  tan A tan 2A)

=> (tan A + tan 2A)/(1 –  tan A tan 2A) = -tan 3A

=> tan (A + 2A) = -tan 3A

=> tan 3A = -tan 3A

=> 2 tan 3A = 0

=> tan 3A = 0

=> A = nπ/3

put n=1 then value of A =π/3

put n=2 then value of A=2π/3

put n=3 then value of A=π

So, according to question values of A are π/3,2π/3 .

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