A triangle has sides A, B, and C. Sides A and B are of lengths 10 and 12, respectively, and the angle between A and B is (5pi)/8 . What is the length of side C?

1 Answer
Deepak G.
Aug 13, 2016

C=18.33

Explanation:

As per law of cosines
C^2=A^2+B^2-2Atimes Btimescos(theta) where A=10;B=12 and theta=(5pi)/8
or
C^2=10^2+12^2-2times10times12timescos((5pi)/8)
or
C^2=100+144-240times(-0.383)
or
C^2=100+144+91.84
or
C^2=335.84
or
C=sqrt335.84
or
C=18.33

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