In quadrilateral ABCD, diagonals AC and BD intersect at point E. Such that AE : EC = BE : ED. Then, ABCD is a parallelogram.
True
Given: In quadrilateral ABCD, diagonals AC and BD intersect each other at E and AE : EC = BE : ED
AEEC=BEED⇒AEBE=ECED
In ΔAEB and ΔCED
AEBE=ECED (given)
∠AEB=∠CED (Vertically opposite angles)
∴ΔAEB∼ΔCED (SAS axiom)
∴∠EAB=∠ECD
∠EBA=∠EDC
But, these are pairs of alternate angles
∴AB∥CD……(i)
Similarly we can prove that
AD∥BC……(ii)
∴ from (i) and (ii)
ABCD is a parallelogram.