Question

Analyze the diagram below and complete the instructions that follow.

Answer 1

Law of Cosines says

$b^2 = a^2 + c^2 - 2 ac \cos B$

$2 a c \cos B = a^2 + c^2 - b^2$

$\cos B = \dfrac{a^2 + c^2 - b^2}{2 a c}$

$\cos B = \dfrac{16^2 + 16^2 - 11^2}{2(16)(16)} = \dfrac{ 391}{512}$

$B = \arccos \dfrac{ 391}{512} \approx 40.2 ^\circ$

Choice C