find the lenght of cd
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Use the distance formula.
[tex]\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}[/tex]
[tex]x_2=7\\x_1=3\\y_2=-8\\y_1=-2[/tex]
[tex]\sqrt{(7-3)^2+(-8-(-2))^2}[/tex]
=[tex]\sqrt{4^2+(-6)^2}[/tex]
=[tex]\sqrt{16+36}[/tex]
=[tex]\sqrt{52}[/tex]
≈7.2111...
So the answer is B! Hope this helped!