A(-4,-1), B(-1,7), C(6,3)
[tex]AB = \sqrt{(-1 - -4)^2 + (7--1)^2}=\sqrt{3^2+8^2}=\sqrt{73}[/tex]
[tex]BC = \sqrt{(6 - -1)^2+(7-3)^2}=\sqrt{49+16}=\sqrt{65}[/tex]
[tex]AC=\sqrt{(6 - -4)^2+(3--1)^2} = \sqrt{116}= 2 \sqrt{29}[/tex]
[tex]\textrm{perimeter} = \sqrt{73} + \sqrt{65} + 2 \sqrt{29} = 27.3766...[/tex]
Answer: 27.4