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Topic: Proving trigonometric identities
Replies: 32   Last Post: Jan 27, 2009 1:59 AM

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 Albert Posts: 282 Registered: 12/9/07
Re: Proving trigonometric identities
Posted: Jan 20, 2009 3:11 AM

On Jan 20, 6:40 pm, Angus Rodgers <twir...@bigfoot.com> wrote:
> On Mon, 19 Jan 2009 23:31:43 -0800 (PST), Albert
>
> <albert.xtheunkno...@gmail.com> wrote:

> >On Jan 20, 6:25 pm, Angus Rodgers <twir...@bigfoot.com> wrote:
> >> Are you familiar with the algebraic identity (a + b)(a - b) = a^2 - b^2?
>
> >Yes I am - are you implying the following steps:
> >(cosx)^2 = (1 + sinx)(1 - sinx)
> >..``..``.= 1 - (sinx)^2
> >?

>
> Yes, I was, but you hardly need to know what I was thinking,
> because the result is clear now, isn't it?

I don't think that it's a proof though. Please enlighten me.

Date Subject Author
1/20/09 Albert
1/20/09 Angus Rodgers
1/20/09 Albert
1/20/09 Angus Rodgers
1/20/09 Albert
1/20/09 Angus Rodgers
1/20/09 Angus Rodgers
1/20/09 Guest
1/20/09 Angus Rodgers
1/20/09 Albert
1/20/09 Angus Rodgers
1/20/09 matt271829-news@yahoo.co.uk
1/21/09 Albert
1/21/09 matt271829-news@yahoo.co.uk
1/23/09 Albert
1/23/09 Angus Rodgers
1/23/09 Angus Rodgers
1/23/09 Passerby
1/23/09 Dave Dodson
1/24/09 Albert
1/24/09 Angus Rodgers
1/24/09 Albert
1/26/09 Albert
1/26/09 Driveby
1/26/09 Albert
1/26/09 A N Niel
1/27/09 Albert
1/20/09 victor_meldrew_666@yahoo.co.uk
1/20/09 Dave Dodson
1/20/09 Pfsszxt@aol.com
1/20/09 Albert