# A triangle has sides A, B, and C. Sides A and B are of lengths 7 and 2, respectively, and the angle between A and B is (5pi)/8 . What is the length of side C?

Jun 18, 2018

color(purple)("Length of side " c = 7.982 " units"
$c = \sqrt{{a}^{2} + {b}^{2} - 2 a b \cos C}$
c = sqrt(7^2 + 2^2 - (2*7*2*cos((5pi)/8))
color(purple)("Length of side " c = 7.982 " units"