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Well it's worth a try - Grin with cat attached
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Well it's worth a try May. 25th, 2006 11:37 am

If I have a triangle of sides d1,d2 and an angle β between them, what is the length of the third side of the triangle?

I don't trust my own geometry as much as I used to...

From: thecesspit
Date: May 25th, 2006 - 10:44 am (Link)
From: azekeil
Date: May 25th, 2006 - 10:48 am (Link)
SOH CAH TOA

Only works for right-angled triangles though.

or

a2 = b2 + c2

(can you tell who's been helping someone with their SATs recently? *grin*)
From: azekeil
Date: May 25th, 2006 - 10:49 am (Link)
a2 is the hypotenuse, btw, and I think that also only works for right-angled triangles.
From: wechsler
Date: May 25th, 2006 - 10:53 am (Link)
Unfortunately my triangles aren't rectilinear.
From: davefish
Date: May 25th, 2006 - 10:53 am (Link)
sqrt ( d1^2 + d2^2 - 2*d1*d2*cos(beta))

Look up the cosine rule.

From: wechsler
Date: May 25th, 2006 - 10:55 am (Link)
Typical - I got all the trig right and then swapped - for +

Thanks!
From: ciphergoth
Date: May 25th, 2006 - 02:09 pm (Link)
The Wikipedia article is rather good:

http://en.wikipedia.org/wiki/Law_of_cosines
From: drdoug
Date: May 25th, 2006 - 12:51 pm (Link)
If I have a triangle of sides d1,d2 and an angle β between them, what is the length of the third side of the triangle?

Easy! d3.

From: drdoug
Date: May 25th, 2006 - 12:52 pm (Link)
... and for extra credit, the other angles are α and γ.
(no subject) - phantas
From: wechsler
Date: May 25th, 2006 - 02:32 pm (Link)
*grin* I thought I was doing pretty well working it out from SOH CAH TOA / Pythagoras to be honest - I *knew* there were specific rules for getting data from a triangle given 3 pieces of data but there's no way I was going to remember their names!
(no subject) - vampwillow