Answer:
[tex]b = 10\sqrt{5-4\cos 26^{\circ}}[/tex]
Step-by-step explanation:
Using the Law of Cosines,
[tex]b^2 = a^2 + c^2 - 2ac \cos B \\ \\ b^2 = 20^2 + 10^2 - 2(20)(10)\cos 26^{\circ} \\ \\ b=\sqrt{500-400\cos 26^{\circ}} \\ \\ =10\sqrt{5-4\cos 26^{\circ}}[/tex]