How do you use the law of cosines to find AB given a triangle ABC with Angle C=41, AC=13 and CB=29?

1 Answer
Dean R.
May 2, 2018

c^2 = a^2 + b^2 - 2 a b cos C

= 29^2+13^2- 2(29)(13) cos 41^circ = 1010 - 754 \ cos 41^circ

c approx 21.00

Explanation:

Typically we label the opposite sides with small letters, so we have angle C=41^circ and b=13 and a=29. The Law of Cosines is

c^2 = a^2 + b^2 - 2 a b cos C = 29^2+13^2- 2(29)(13) cos 41^circ = 1010 - 754 cos 41^circ

c approx 21.00

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