Prove that if the diagonals of a quadrilateral bisect each other, then it is a parallelogram. [4 MARKS]
Diagram : 1 Mark
Concept : 1 Mark
Proof : 2 Marks
Consider ΔAOD and ΔCOB.
AO=CO [Given]
BO=DO [Given]
∠AOD=∠COB [vertically opposite]
∴ΔAOD≅ΔCOB. [SAS conguency]
∠ADO=∠CBO [CPCTC]
Thus, AD||BC (Alternate angles are equal)--------(i)
Similarly, We can prove
ΔDOC≅ΔBOA.
⇒AB||DC -----(ii)
Combining (i) and (ii), we can conclude that ABCD is a parallelogram.