A triangle has sides A, B, and C. Sides A and B are of lengths $10$ and $12$ , respectively, and the angle between A and B is $(2pi)/3$ . What is the length of side C?

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Answer 1 · 2018-04-30T14:49:20

c=19.07878403

Cosine rule $c^2=a^2+b^2-2bc$ CosA

$c^2=10^2+12^2-{2xx10xx12xxCos(2/3pi)}$

$c^2=244-{-120}$

$c=sqrt 364$

c=19.07878403

A triangle has sides A, B, and C. Sides A and B are of lengths 1010 and 1212, respectively, and the angle between A and B is (2pi)/3 (2pi)/3 . What is the length of side C?