Alex G.
asked • 02/15/18Triangle Question
In triangle ABC a=4 b=11 and c=8 find m<B?
I need step by step if possible so I can understand my error.
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1 Expert Answer
Mark M. answered • 02/16/18
Tutor
4.9
(954)
Retired Math prof with teaching and tutoring experience in trig.
Using the Law of Cosines, b2 = a2 + c2 - 2accosB
121 = 16 + 64 - 2(4)(8)cosB
41 = -64cosB
cosB = -0.640625
∠B = Arccos(-0.640625) ≈ 129.84°
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Mark M.
02/15/18