Answer:
Step-by-step explanation:
Formula :
[tex]\sf \boxed{\sf D=\sqrt{(x_1-x_2)^2+(y_1-y_2)^2}}[/tex]
Then :
[tex]\sf DE=\sqrt{(2-3)^2+(1-5)^2} }= \sqrt{17} \\\\ EF=\sqrt{(3-6)^2+(5-2)^2} =\sqrt{18} \\\\DF=\sqrt{(2-6)^2+(1-2)^2}= \sqrt{17}[/tex]
Since [tex]\sf DE=DF[/tex] DEF isosceles triangle