Chapter 7 - Section 7.2 - The Law of Cosines - 7.2 Problem Set - Page 381: 63

d. 6.4

Based on the cosine formula that $c^{2}$ = $a^{2}$ + $b^{2}$ - 2$ab$ $\cos$ $C$ We input the values of $a$ = 6.8, $b$ = 8.4, and $C$ = $48^{\circ}$ as $c^{2}$ = $6.8^{2}$ + $8.4^{2}$ - 2$(6.8)(8.4)$ $\cos$ $48^{\circ}$to get an answer of 40.35851953 we then find $\sqrt 40.35851953$ to provide the final answer of 6.3528 which can be rounded up to 6.4