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#1 2008-01-30 16:44:24
- jcd293jd
- Guest
double angle trigonometric identities problems
Here's a few I'm having trouble with:
1. [cot(x)+tan(2x)] = [{cot(x)}/{cos(2x)}]
2. [cot(x)-tan(x)]/[cot(x)+tan(x)] = cos(2x)
#2 2008-01-30 19:27:01
- Identity
- Member
- Registered: 2007-04-18
- Posts: 934
Re: double angle trigonometric identities problems
Question 2
EDIT: Sorry about that ! I think the method's quite 'normal' too 
Last edited by Identity (2008-01-31 08:20:57)
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#3 2008-01-31 06:33:29
- mathsyperson
- Moderator
- Registered: 2005-06-22
- Posts: 4,900
Re: double angle trigonometric identities problems
Wherever you've put sin²x - cos²x, it should actually be cos²x - sin²x.
Very nice method though, other than that.
Why did the vector cross the road?
It wanted to be normal.
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