Use the Law of Cosines to solve the triangle a 42 b 34 c

Use the Law of Cosines to solve the triangle. a = 42, b = 34, c = 57 A = degree B = degree C = degree

Solution

c^2 = a^2 + b^2 -2abcosC

cosC = (a^2 +b^2 -c^2)/2ac = (42^2 + 34^2 - 57^2)/2*42*34

= -0.115

C = 96.6 deg

cosA = (b^2 + c^2 - a^2)/2bc

= ( 34^2 + 57^2 - 42^2)/(2*34*57)

= 0.681

A = 47.05

B = 180 - A - C = 36.35 deg