Answer:
Using midpoint theorem,
The segment joining two sides of a triangle at the midpoints of those sides is parallel to the third side and is half the length of the third side.
∴ DF || BC
The opposite sides of the quadrilateral are parallel and equal.
BDFE is a parallelogram
DFCE is a parallelogram.
In ∆ABC and ∆EFD,
∠???????????? = ∠???????????? (???????????????????????????????? ???????????????????????? ???????? ???? ????????????????????????????????????????????????????)
∠???????????? = ∠???????????? (???????????????????????????????? ???????????????????????? ???????? ???? ????????????????????????????????????????????????????)
By AA similarity criterion,
∆ABC ~ ∆EFD
If two triangles are similar, then the ratio of their areas is equal to the squares of their corresponding sides.
Hence, the ratio of the areas of ∆DEF and ∆ABC is 1 : 4.