Question

ΔABC has three sides with these lengths: AB = 9, BC = 40, and CA = 41. What is the value of cos C?

Answer 1

To find the angle measure, the inverse of cosine must be used.
Recall from SOH CAH TOA that Cosine is Adjacent/Hypotenuse
So our set up is:
\[\cos^{-1} \theta=\frac{ 40 }{ 41 }\]