Sine Law and Cosine Law

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Phanzanu
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Sat Oct 21, 2006 6:19 pm
Phanzanu says... · Sat Oct 21, 2006 6:19 pm
I'm going nuts! If I can prove the Sine and Cosine Law and pass it on Monday by 1:40pm GMT+08 in my Math class, then I can gain 2 bonus points for my Math 4 periodical exam (believe me, 2 points are a luxury in my school). However, I'm having a mental block... so... ideas go boing! from my head.

Here's the Cosine Law (capitals for lengths, and lowercase for the angle):

A2 = B2 + C2 - 2BCcosa.

A-squared is equal to B-squared plus C-squared minus 2 (B) (C) cosine angle-alpha.

Thanks!
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Snoink
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Tue Oct 24, 2006 5:06 am
Snoink says... · Tue Oct 24, 2006 5:06 am
Oops... sorry. Didn't see this.

Here's the proof, if you're still curious:

http://www.cut-the-knot.org/pythagoras/cosine.shtml
Ubi caritas est vera, Deus ibi est.

"The mark of your ignorance is the depth of your belief in injustice and tragedy. What the caterpillar calls the end of the world, the Master calls the butterfly." ~ Richard Bach

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Phanzanu
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Tue Oct 24, 2006 7:53 am
Phanzanu says... · Tue Oct 24, 2006 7:53 am
Oh, thanks anyway. :)

The proof there is different from the one I found... hmm. It's true that there is more than one approach to every problem. :P
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Snoink
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Tue Oct 24, 2006 11:21 pm
Snoink says... · Tue Oct 24, 2006 11:21 pm
Oh yes! The higher you go in math, the more proofs there are. It's crazy, really.
Ubi caritas est vera, Deus ibi est.

"The mark of your ignorance is the depth of your belief in injustice and tragedy. What the caterpillar calls the end of the world, the Master calls the butterfly." ~ Richard Bach

Moth and Myth <- My comic! :D
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