Given ABC with a = 6, b = 18, and mC 88° , find c. Round the cosine value to the nearest thousandth and answer to the nearest hundredth.

Question

Now I got 28.32

Answer 1

c^2 = a^2 + b^2 - 2 a b cos C
88 is very close to 90 so approximately
c^2 = 36 + 324 = 360
c = about 19 so not 28.whatever