SOLUTION: A triangle has sides of length 2 cm, 8 cm and 9 cm. Calculate the value of the largest angle in this triangle.

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Question 967028: A triangle has sides of length 2 cm, 8 cm and 9 cm.
Calculate the value of the largest angle in this triangle.
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Use the law of cosines,
9%5E2=2%5E2%2B8%5E2-2%282%29%288%29cos%28theta%29
81=4%2B64-32cos%28theta%29
-16cos%28theta%29=13
cos%28theta%29=-13%2F32
theta=113.97