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In a triangle ABC, the angle at B is 108 degrees, the length of side BC is 16, and the length of side AB is 12. To 2 decimal places, what is the length of side AC?

So i worked out and out and got this answer 22.77 is that right? I used cosine rule.

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closed as too localized by Austin Mohr, William, Norbert, tomasz, J. M. Oct 7 '12 at 13:27

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up vote 4 down vote accepted

Using cosine rule, $AC^2=16^2+12^2-2(16)(12)\cos 108^\circ$, so you are right.

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