SOLUTION: I have a law of cosines question: One side is 4cm and another is 5cm (this is NOT a right triangle). the angle between the sides is 50 degrees. I need to find the other sid

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Question 879347: I have a law of cosines question:
One side is 4cm and another is 5cm (this is NOT a right triangle).
the angle between the sides is 50 degrees.
I need to find the other side and the two other angles. Im guessing I use law of cosines and law of sines. Whenever I use law of cosines I get 1.5 for the other side which doesnt make sense. What am I doing wrong?
Also, i need to find the area of this triangle.
Found 2 solutions by solver91311, Edwin McCravy:
Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!


Show your work with the law of cosines that gets you to C = 1.5, and I'll tell you what you did wrong.

John

My calculator said it, I believe it, that settles it
The Out Campaign: Scarlet Letter of Atheism

Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!
This is a case of SAS, so we use the law of cosines.



c%5E2%22%22=%22%22a%5E2%2Bb%5E2-2%2Aa%2Ab%2Acos%28C%29

c%5E2%22%22=%22%224%5E2%2B5%5E2-2%2A4%2A5%2Acos%28%2250%B0%22%29

c%5E2%22%22=%22%2216%2B25-40%2Acos%28%2250%B0%22%29

c%5E2%22%22=%22%2241-40%2A%28.6427876097%29

c%5E2%22%22=%22%2215.28849561

c%22%22=%22%22sqrt%2815.28849561%29

c%22%22=%22%223.91005059

You can either finish by using the law of sine or 
you can use the law of cosines again.

cos%28A%29%22%22=%22%22%28b%5E2%2Bc%5E2-a%5E2%29%2F2bc


You already have cē = 15.28849561

cos%28A%29%22%22=%22%22%284%5E2%2B15.28849561-5%5E2%29%2F%282%2A4%2A15.28849561%29

cos%28A%29%22%22=%22%22%284%5E2%2B15.28849561-5%5E2%29%2F%282%2A4%2A3.91005059%29

A = 78.4024367

Then to find C add those angles and subtract from 180°

B = 51.5975633

Edwin