Answer: A) EF > DF
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Explanation:
Recall that for any triangle, the three angles always add to 180
D+E+F = 180
60+40+F = 180
100+F = 180
F = 180-100
F = 80
Angle F being 80 degrees makes it the largest angle of the triangle.
The side opposite angle F is the longest side. ED is the longest side
The shortest side is DF because it is opposite the smallest angle
Therefore, this must mean EF > DF
