2025 AHS PRELIMS P1 Q11

\(ABCD\) is a trapezium where \(DC\) is parallel to \(AB\). Diagonals \(AC\) and \(BD\) intersect at \(O\). \(DO=CO\).

1. Name a pair of similar isosceles triangles.[1]
2. Show that triangle \(ABC\) and triangle \(BAD\) are congruent. Give a reason for each statement you make.[3]