Here's another method to prove condition ii (\(\overline{AC}\perp\overline{DB}\)). I will utilize a two-column proof:
\(AD=CD\) \(AB=CB\) | Given |
\(\overline{AD}\cong\overline{CD}\) \(\overline{AB}\cong\overline{CB}\) | Definition of congruent segments |
Figure \(ABCD\) is a kite | Definition of a kite (If a quadrilateral has two unique pairs of sides that are congruent, then the figure is a kite) |
\(\overline{AC}\perp\overline{DB}\) | Property of a kite (Diagonals of a kite are perpendicular) |