Find c if a = 2.8 mi, b = 3.15 mi and ∠ C = 40.9 degrees

Question

Find  if  mi,  mi and  degrees

c=

Answer 1

c = square root of (2.8^2 + 3.15^2 - 2(2.8)(3.15)(cos40.9)

just use the law of cosines

c^2 = sum of squares of the other two sides - twice the product of the other two sides times the cosine of C