In the parallelogram ABCD, ad and BC are taken as sides respectively, and the equilateral △ ade and equilateral triangle BFC are made outside the parallelogram ABCD

In the parallelogram ABCD, ad and BC are taken as sides respectively, and the equilateral △ ade and equilateral triangle BFC are made outside the parallelogram ABCD

prove:
ABCD is a parallelogram
∴AD=BC,∠ADB=∠DBC
And ∵ ⊿ ade and ⊿ BCF are equilateral triangles
∴DE=AD=BC=BF,∠EDA=∠CBF=60º
∵∠EDB=∠EDA+∠ADB,∠DBF=∠CBF+∠DBC
■ ∠ EDB = ∠ DBF [equal internal stagger angle]
‖ ed / / BF [add ed = BF]
The quadrilateral ebfd is a parallelogram, and BD and EF are diagonals
The BD and EF are equally divided