Answer: choice D) 11.7
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Work Shown:
Apply the Law of Sines to get the following. Make sure your calculator is in degree mode.
[tex]\frac{\sin(A)}{a}=\frac{\sin(B)}{b}=\frac{\sin(C)}{c}\\\\\frac{\sin(A)}{a}=\frac{\sin(C)}{c}\\\\\frac{\sin(20)}{4}=\frac{\sin(87)}{c}\\\\c*\sin(20)=4*\sin(87)\\\\c=\frac{4*\sin(87)}{\sin(20)}\\\\c\approx 11.6791897\\\\c\approx 11.7\\\\[/tex]
So that's why the answer is choice D) 11.7
