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# Help with a Trig question watch

1. It says

Prove that 2tanx/(1+tan^2x) = sin2x which I'm fine with, easy.

Then it says hence or otherwise find the exact value of tan(15 degrees) in the form a + root(3) where a and b are integers.

I think I'm on the right track by finding the sin of 30 degrees which is a half but then not really sure what to do. Ended up with a quadratic equation and when I solved that using the quadratic formula I think I got the right answer as it matched the answer in the book but I also got another answer of 2- root(3) but the anwser in the book is only root(3) + 2 which is the other answer I got..

Cheers,
Ross
2. (Original post by rosschambers1987)
It says

Prove that 2tanx/(1+tan^2x) = sin2x which I'm fine with, easy.

Then it says hence or otherwise find the exact value of tan(15 degrees) in the form a + root(3) where a and b are integers.

I think I'm on the right track by finding the sin of 30 degrees which is a half but then not really sure what to do. Ended up with a quadratic equation and when I solved that using the quadratic formula I think I got the right answer as it matched the answer in the book but I also got another answer of 2- root(3) but the anwser in the book is only root(3) + 2 which is the other answer I got..

Cheers,
Ross
Am I missig something or did b come out of nowhere?
3. Woops sorry it should say in the form a + broot(3)

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