Law of Cosines. Find the missing angles for this triangle.

Question

anonymous · Answer

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anonymous · Answer

Could you show us what you've done so far please?

e.mccormick · Answer

The Law of Cosines says:$$ c^2=a^2+b^2-2ab \cos (C)$$Now, you have the sides, but not the angle.  So you need to do a little algebra to start.$$ c^2=a^2+b^2-2ab \cos (C)\implies  c^2-a^2-b^2=-2ab \cos (C) \implies  \frac{c^2-a^2-b^2}{-2ab}= \cos (C) $$Now you can find the cosine of C.  Well, through arccosine, you can find angle C.

Also, there are three forms of the Law of Cosines.  They are for doing different angles.  You could adjust this to solve the largest angle first, which has some benefits if you plan to use the Law of Sines after doing the first one by cosines.

I hope that gives you a place to start.  If you get stuck, post how far you got and where the trouble is.