Answer: 56.0°
Step-by-step explanation:
Use the Law of Cosines:
b² = a² + c² - 2ac · cos B
20² = 22² + 18² - 2(22)(18) · cos B
400 = 484 + 324 - 792 · cos B
400 = 804 - 792 · cos B
-404 = - 792 · cos B
0.5151 = cos B
cos ⁻¹ (0.5151) = B
55.99 = B
56.0 ≈ B
