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#1 2012-10-21 13:43:54
- woweycowey
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Please Help with this Trigonometry Proof!
If anyone could help with this that would be amazing, im just finding myself stuck.
(sinxcosx)/((cosx^2)-(sinx^2)) = ((tanx)/(1-tanx^2))
#2 2012-10-21 19:00:48
- bob bundy
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Re: Please Help with this Trigonometry Proof!
hi woweycowey
Welcome to the forum!
I think you mean sin^2 (x) rather than sinx^2 ie.
Anyway start with the left hand side:
Divide top and bottom by
and it comes out straight away.
Bob
You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei
#3 2012-10-22 01:25:30
- zetafunc.
- Guest
Re: Please Help with this Trigonometry Proof!
Bob bundy's way is the best way since it is only one step. Here is another neat way to do it but it takes a bit longer (it's how I did it though);
I still prefer the one-step method though, haha. So this post is a little redundant...
#4 2012-10-22 02:24:07
- bob bundy
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Re: Please Help with this Trigonometry Proof!
hi zetafunc,
That's what I thought as well to start with. I think the double angle formulas jump out at you.
But I thought the OP might not have met them so I looked to see if I could bypass them. The tan2A formula comes from dividing by cos so I tried that instead and nearly fell off my chair.
Good to offer a choice so not redundant. 
Bob
You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei