In ΔDEF, DE = 11, EF = 9, and angle E = 140°. Which equation correctly uses the law of cosines to solve for the third side?
A
e2 = 112 + 92 − 2(11)(9)cos(140°)B
112 = e2 + 92 − 2e(9)cos(140°)C
92 = e2 + 112 − 2e(11)cos(140°)D
e = 11 + 9 − 2(11)(9)cos(140°)