CPM Homework Help : INT3 Problem 8-105

For $ΔABC$ , determine $m∠C$ given that $BC = 30, AC = 15$ , and $AB = 21$ .

Hint:

Use the Law of Cosines:
$c^{2} = a^{2} + b^{2} − 2ab\left(\text{cos}C\right)$

Answer:

$m∠C ≈ 40.5^\circ$