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Subject: 
Re: Geometry
Newsgroups: 
lugnet.off-topic.geek
Date: 
Wed, 28 Jul 1999 16:49:03 GMT
Viewed: 
134 times
  
In lugnet.off-topic.geek, Fredrik Glöckner writes:
Suppose I have a triangle, in which I know the lengths of the three
sides.  I want to find the corresponding angles inside the triangles.
Is there a quick and simple way to do that?

I know that I can divide the triangle into two triangles with a 90°
angle each, and then solve a set of two equations with two unknowns.
But that is a bit of a hassle, especially if there is a simpler way.

Fredrik

Reaching way, way back...  Can you use the law of sines?

sin A / a = sin B / b = sin C / c

Seems like there's a step missing though.

Perhaps the law of cosines is better:

a*a + b*b + c*c = -2bc*cos(A)

Solve for A?

Anyhow, good luck.

Don



Message has 1 Reply:
  Re: Geometry
 
(...) With a, b and c being the length of the sides, and A being the angle of the edge just opposite of a? Why, that looks just perfect! Thanks! (I'm used to using A, B and C for the lengths and the corresponding lowercase letters for the angles, so (...) (25 years ago, 29-Jul-99, to lugnet.off-topic.geek)

Message is in Reply To:
  Geometry
 
Suppose I have a triangle, in which I know the lengths of the three sides. I want to find the corresponding angles inside the triangles. Is there a quick and simple way to do that? I know that I can divide the triangle into two triangles with a 90° (...) (25 years ago, 28-Jul-99, to lugnet.off-topic.geek)

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