Chapter 14 - Trigonometric Identities and Equations - 14-5 The Law of Cosines - Practice and Problem-Solving Exercises - Page 939: 7

$x\approx37.1$

The Law of Cosines must be used in form $b^{2}=a^{2}+c^{2}-2ac\cdot23\cos{B}$. $b^{2}=a^{2}+c^{2}-2ac\cos{B}$ $x^{2}=23^{2}+20^{2}-2(23)(20)\cos119°$ $x^{2} \approx 1375.0249$. $x \approx \sqrt {1375.0249}$ $x \approx 37.1$