Chapter 9 Quadratic Relations and Conic Sections - 9.1 Apply the Distance and Midpoint Formulas - 9.1 Exercises - Skill Practice - Page 617: 24

scalene

The distance formula from $P_1(x_1,y_1)$ to $P_2(x_2,y_2)$ is $d=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}$. Hence here: $a=\sqrt{(3-5)^2+(5-(-3))^2}=\sqrt{68}$, $b=\sqrt{(3-7)^2+(5-(-3))^2}=\sqrt{80}$, $c=\sqrt{(5-7)^2+(-3-(-3))^2}=\sqrt{4}=2$, thus the triangle is scalene.