Given: AC and BD bisect each other
AC and BD are intersects at the point E
So, BE = DE and AE = CE
For the triangles : BEC and DEA
1. BE = DE (proved)
2. m∠ BEC = m∠DEA ( vetical angles are congruent )
3. AE = CE ( proved )
So, the triangles are congruent by SAS [ side - angle - side ]