Posted by **Michael** on Thursday, April 7, 2011 at 9:14pm.

Suppose a triangle has side lengths of 6, 7, and 10. What best describes it? Acute, right, obtuse, or not enough information?

- geometry -
**drwls**, Thursday, April 7, 2011 at 9:28pm
It is a scalene triangle. One angle is obtuse, and no two are equal.

The angle opposite the longest side is C. According to the Law of Cosines,

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

Since c^2 is greater than a^2 + b^2, cos C is negative, so C is obtuse ( >90 degrees)

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