My calulator is broken and I need this tomorrow. In triangle abc, a=7, b=9 and c=11. Find the three angle measures of the triangle. Using sin

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- Apr 2nd 2008, 03:38 PM #1

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- Apr 2nd 2008, 03:42 PM #2
using sin what? you cannot use the law of sines here. and this is not a right triangle, so Pythagoras or trig ratios won't help us. use the law of cosines.

$\displaystyle a^2 = b^2 + c^2 - 2bc \cos A$

you can use that to find angle A. Similar formulas can get you angles B and C. Or, once you have angle A, you can use the law of Sines to get the other angles. Your choice