A triangle has sides A, B, and C. Sides A and B are of lengths #2# and #7#, respectively, and the angle between A and B is #(7pi)/8 #. What is the length of side C?

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Answer 1 · 2016-06-30T02:20:29

Given
#"Side A"=2,"Side B"=7#

#theta="Angle between" A & B=(7pi)/8#
#"Side C"= ?#

We know

#C^2=A^2+B^2-2ABcostheta#

#=>C^2=2^2+7^2-2*2*7*cos(7pi/8)#

#=>C=sqrt(2^2+7^2-2*2*7*cos(7pi/8))#

#=>C~~8.88#