Answer:
Step-by-step explanation:
[tex]c^2=a^2+b^2-2ab\cos\theta\\ \\ \theta=\cos^{-1}\frac{a^2+b^2-c^2}{2ab}\\ \\ \theta=\cos^{-1}\frac{55^2+50^2-90^2}{2(55)50}\\ \\ \theta\approx117.9^o[/tex]
