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Alain Fontaine

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Mar 29, 1995, 3:00:00 AM3/29/95
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Hello All!

I need help with the following:

Prove that if a+b+c=PI, we have:

cos^2(a)+cos^2(b)+cos^2(c)+2*cos(a)*cos(b)*cos(c) = 1

I really don't know how to do it :), after 3 hours of trying to find it...

Greetings,
Alain


Alain Fontaine

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Mar 29, 1995, 3:00:00 AM3/29/95
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Hello Alain,

Alain Fontaine wrote in a message to All:

AF> I need help with the following:

AF> Prove that if a+b+c=PI, we have:

AF> cos^2(a)+cos^2(b)+cos^2(c)+2*cos(a)*cos(b)*cos(c) = 1

AF> I really don't know how to do it :), after 3 hours of trying
AF> to find it...

Ok, after a coffee pause, I found it in 10 minutes :)))) Thanks for reading
anyway. I just had to use the cos(a)*cos(b) stuff twice, et voila.

Greetings,
Alain


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