Chapter 9 Quadratic Relations and Conic Sections - 9.1 Apply the Distance and Midpoint Formulas - 9.1 Exercises - Skill Practice - Page 617: 27

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: $a=\sqrt{(-4-(-2))^2+(1-6)^2}=\sqrt{29}$, $b=\sqrt{(-4-0)^2+(1-(-1))^2}=\sqrt{20}$, $c=\sqrt{(-2-0)^2+(6-(-1))^2}=\sqrt{53}$, thus the triangle is scalene.