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Flikerator

Wed Apr 19, 2006 7:15 am


Angle

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If im given three coordinates how do I find the angle of the three points? (That they make with each other).

Like (2,1)    (3,0)     (5,7)

At (3,0) the forumula for the angle would be-


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Andy

Wed Apr 19, 2006 9:59 am



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ever heard of cosine law?

this shouldnt be in general programming.

moved


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MysticVegeta

Wed Apr 19, 2006 1:52 pm



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Find distance between them (Math.Distance)
Name the sides, A, B, C;

A^2 = B^2 + C^2 - 2*B*C*cos(A)

plugin, vals, find cos A, use inverse get angle


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codemage

Thu Apr 20, 2006 9:05 am



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That's odd.  I distinctly remember the last time I used COS law, and it was thinly sliced cabbage.


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zylum

Thu Apr 20, 2006 10:42 am



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ha ha ha!   :eh:  :doh:


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Flikerator

Thu Apr 20, 2006 11:39 am



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I find point a,b, and c and the distances between them. Then I use the cosine law to find the angle. The only problem is when I have an angle > 180 it takes the reflex of it. I know why, but im not really sure how to fix it ^^;

http://ic1.deviantart.com/fs10/i/2006/110/4/6/Convex_Polygon___not_so_much_by_Jack_Skellingtin.jpg
http://ic1.deviantart.com/fs10/i/2006/110/4/6/Convex_Polygon___not_so_much_by_Jack_Skellingtin.jpg


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Andy

Thu Apr 20, 2006 12:04 pm



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why dont you check if it's an obtuse angle and if it is just find the reflex of the reflex