Answer:
ΔDEF is not a right triangle because no two sides are perpendicular.
Step-by-step explanation:
The coordinates of the vertices of ΔDEF are given to be D(-4,1), E(3,-1) and F(-1,-4).
Now length of DE is given by [tex]\sqrt{(-4-3)^{2}+(1-(-1))^{2} } =\sqrt{53}[/tex] units
length of EF is given by [tex]\sqrt{(3-(-1))^{2}+(-1-(-4))^{2} }=\sqrt{25}[/tex] units
and length of FD is given by [tex]\sqrt{(-4-(-1))^{2}+(1-(-4))^{2} } =\sqrt{34}[/tex] units.
Therefore, 53 ≠ 25+34
Hence, the length of the sides does not support the Pythagoras theorem.
So, ΔDEF is not a right triangle because no two sides are perpendicular. (Answer)