Reply-To: "Kevin Aylward"
From: "Kevin Aylward"
References: <firstname.lastname@example.org> <2ltr9.338$cV6.email@example.com> <3DAED797.firstname.lastname@example.org> <3DAEDE54.email@example.com>
Subject: Re: How does a mixer work?
X-Newsreader: Microsoft Outlook Express 6.00.2800.1106
Date: Thu, 17 Oct 2002 19:56:28 +0100
NNTP-Posting-Date: Thu, 17 Oct 2002 19:57:26 BST
"Jim Thompson" wrote in message
> On Thu, 17 Oct 2002 15:59:24 GMT,
> Fred Bloggs ,
> In Newsgroup: sci.electronics.design,
> Article: <3DAEDE54.firstname.lastname@example.org>,
> Entitled: "Re: How does a mixer work?",
> Wrote the following:
> |Kevin Aylward wrote:
> |> "Fred Bloggs" wrote in message
> |> news:3DAED797.email@example.com...
> |>>Kevin Aylward wrote:
> |>>>The basic reason is based on a standard trigonometric result.
> |>>>Sin(A)*Sin(B)= 0.5*(Cos(A-B) + cos(A+B))
> |>>Huh? And which alternative reality is this?
> |> This one. In what universe is this not true?
> |Seriously , Kevin, cos(A+B)=cos(A)cos(B)-sin(A)sin(B). If it's any
> | I like your explanation the best.
> (1) cos(A+B) = cos(A)cos(B)-sin(A)sin(B)
> (2) cos(A-B) = cos(A)cos(B)+sin(A)sin(B)
> (2)-(1)-> cos(A-B)-cos(A+B) = 2*sin(A)sin(B)
> or sin(A)sin(B) = 0.5*(cos(A-B)-cos(A+B))
> so Kevin has a sign error ;-)
Well, this is from memory....Actually, I have no idea why I typed the
plus sign, it obvious that it has to be a minus, anyway, the exact
detail don't really matter...
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