SOLUTION: A triangle has sides of length 5,8,and 10. What is the measure of its largest angle?

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Question 478552: A triangle has sides of length 5,8,and 10. What is the measure of its largest angle?
Answer by Alan3354(69443) About Me  (Show Source):
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A triangle has sides of length 5,8,and 10. What is the measure of its largest angle?
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It's opposite the longest side.
Use the Cosine Law:
c%5E2+=+a%5E2+%2B+b%5E2+-+2ab%2Acos%28C%29
10%5E2+=+5%5E2+%2B+8%5E2+-+5%2A8%2Acos%28C%29
cos(C) = (100 - 89)/-40 = -11/40
C = ~ 105.96 degs