SOLUTION: In triangle ABC a=4 b=11 and c=8 find m∠B?

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Question 1109653: In triangle ABC a=4 b=11 and c=8 find m∠B?
Answer by Edwin McCravy(20056)   (Show Source): You can put this solution on YOUR website!
In triangle ABC a=4 b=11 and c=8 find m∠B?


For the SSS case, we use the law of cosines:

 b² = a² + c² - 2∙a∙c∙cos(B)

11² = 4² + 8² - 2∙4∙8∙cos(B)
121 = 16 + 64 - 64∙cos(B)
121 = 80 - 64∙cos(B)
 41 = -64∙cos(B)
 = cos(B)

Use inverse cosine key on your calculator

B = 129.83844°

Ewin
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