We are asked to solve for the value of cos C on which given side measurements are enumerated below:
AB = 9
BC = 40
CA = 41
Solving for the value of cos C, we will apply Law of Cosines such as the solution is shown below:
cos C = BC² + CA² - AB / (2*BC*CA)
cos C = 40² + 41² - 9² / (2*40*41)
cos C = 0.97561
The answer for the value of cos C is "0.97561".