Problem
24. Using the law of cosine, which of the following should be used to find the measure of side $c$ ? A. $c^{2}=a^{2}+b^{2}-2 a b(\cos C)$ C. $c^{2}=a^{2}+b^{2}-2 a b(\cos A)$ B. $c^{2}=a^{2}+b^{2}-2 b c(\cos B)$ D. $c^{2}=a^{2}+b^{2}-2 b c(\cos C)$
Solution
Step 1 ：Use the law of cosine to find the measure of side c: \(c^{2} = a^{2} + b^{2} - 2ab(\cos C)\)
Step 2 ：The final answer is: \(\boxed{c^{2} = a^{2} + b^{2} - 2ab(\cos C)}\)
