A triangle has sides A, B, and C. Sides A and B are of lengths #7# and #5#, respectively, and the angle between A and B is #(7pi)/12 #. What is the length of side C?

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Answer 1 · 2018-07-23T07:31:59

The side #c=9.6u#

Apply the cosine rule

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

The sides are

#a=7#

#b=5#

And

#hatC=7/12pi#

Therefore,

#c^2=7^2+5^2-2*7*5*cos(7/12pi)#

#c^2=92.12#

#c=sqrt92.12=9.6u#