Find BC.
https://latex.artofproblemsolving.com/f/e/4/fe45662f573f87e30f9f30d0b1ef1f94b4c22fc2.png
By the Law of Cosines:
a2=c2+b2−2cbcosA (¯BC)2=(7√2)2+(6)2−2(7√2)(6)cos(45°) (¯BC)2=98+36−(84√2)(√22) (¯BC)2=98+36−84 (¯BC)2=50 ¯BC=√50 ¯BC=5√2