A triangle has sides A, B, and C. Sides A and B are of lengths #5# and #2#, respectively, and the angle between A and B is #(11pi)/12 #. What is the length of side C?

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Answer 1 · 2015-12-19T17:15:44

#c^2=a^2+b^2-2abcos(C)#

The angle between sides #a# and #b# will be angle #C#.

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Plug in what you know.

#c^2=5^2+2^2-2(2)(5)cos((11pi)/12)#

Thus, this can be simplified and plugged into a calculator (remember to be in radian mode.

#"side"# #c=sqrt(29-20cos((11pi)/12))#