A triangle has the following characteristics a 20 b 60 c

A triangle has the following characteristics.

a = 2.0

b = 6.0

c = 7.0

Solve for angle C using the Law of Cosines. Give (approximate) numerical answers rounded to one decimal place.

Solution

cosC = (a^2 + b^2 - c^2)/2ab

= ( 2^2 + 6^2 - 7^2)/2*2*6

= -0.375

C = 112.02 = 112 deg