Solve for x

[jman15]

I have a triangle that is a non-right triangle. It has 2 sides with lengths 18 and 28 with a degree between them of 120. I need to find the third side. (x)

Please help and give full answer

 

[Aladdin]

Law of cosines :

a^2 = b^2 + c^2 -2bc(cos(alpha))

 

[mmm4444bot]

Did you see my other response?

Side x is opposite theta, so it's the following form.

\(\displaystyle x^2 \;=\; 18^2 \;+\; 28^2 \;-\; 2(18)(28) \ cos(120^\circ)\)