Step-by-step Answer:
Two ways to find the answer.
1. Using sine rule, we have
d/sin(D) = f/sin(F) (d=EF, f=DE=3)
cross multiply and solve for d:
d=f*(sin(D)/sin(F) = 3*sin75/sin50 = 3.783.
2. using the theorem that if angle D is greater than angle F, then the length of the opposite side of D is also smaller than the opposite side of F.
Here D>F, so d>f. The only answer choice greater than 3 is 3.8, so there.
