How to find a triangle angle when all three sides are known

[Poweranimals]

Well, does anyone know how to solve for an angle of a triangle if you already have the measurements of all three sides? Any help would be appreciated.

 

[CinderBlockFist]

Yes, you can use the law of Cosines to find the measure of any angle given the three sides, or the third side given an angle and two sides.

Try this link : http://hyperphysics.phy-astr.gsu.edu/hbase/lcos.html

Remember, in the diagram, the angles are the Capital A, B, and C, and the sides are the opposite and are little a, b , and c.

 

[humanino]

That is more than a hint !

 

[recon]

You may still want to find out why the Law of Cosines is valid. I strongly suggest that you do. Check out the proof here.