Question #9637f

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Answer 1 · 2017-09-17T03:36:10

#tan x+tan2x=tan3x# is not a true relationship, and it violates the laws of mathematics. Therefore, it cannot be proved.

For this "proof," we will use substitution of a sample angle value to test with. Suppose #x = 30^@# --> #2x = 60^@#, --> and #3x = 90^@#.

If the given identity is true, then we must have:

#tan 30 + tan 60 = tan 90#

#sqrt3/3 + sqrt3 = (4sqrt3)/3#

That is not true, because #tan 90# is indefinite.

Therefore, this identity is not true.

I hope that helps!