Step-by-step explanation:
In triangle ABC
ABD=ACD-------------(1)
In triangle abd,BE is the median
Abe = bed-------------(2)
Now,
ABD = BED
=2 (BED)-----------(3)
ABC=ABD + ACD
ABC = 2(ABD)----- using(1)
ABC =2 * 2(BED)---- using(3)
ABC = 4(BED)
So,
(BED) = 1/4(ABC)
Hope It's Helps!