Writing expression in terms of t=tan x/2

Stuck on this one question.

3cosx + 4sinx, write in terms of t=tan x/2

The answer is 3 - 3t^2 +8t / 1+t^2

Sorry I just wrote it in normal text, in a hurry lol.

Thanks

Hello icesta1

Quote:

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Originally Posted by icesta1

Stuck on this one question.

3cosx + 4sinx, write in terms of t=tan x/2

The answer is 3 - 3t^2 +8t / 1+t^2

Sorry I just wrote it in normal text, in a hurry lol.

Thanks

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Provided you know the formulae:

and

I don't see what the problem is. Just substitute these into the expression, and the answer follows immediately:

Have you seen these formulae before?

Grandad

Hm... its funny cause I actually have that written in my book lol. I think i might have been looking at the wrong answer while doing it >_< lol.

Thanks anyways :)

EDIT: Nvm i got it