In the given figure, AD=DB and AE=EC. The ratio, BC:DE=
It is given that, AD=DB
i.e, AD=12AB
Also, as AE=EC
we have, AE=12AC
By mid-point theorem, we know that the line segment connecting the midpoints of two sides of a triangle is parallel to the third side and is one half of the third side.
i.e, DE∥BC and
DE = 12 BC
Thus, BC:DE=2:1