Question: abcd is a quadrilateral with diagonals ac and bd?
Answer: If the diagonals AC and BD of a quadrilateral ABCD intersect O and separate the quadrilateral in four triangle are equal, can you prove ABCD is a parallelogram? Given that all triangles formed by diagonals of the quadrilateral are equal. ... We proved that diagonals of ABCD bisect each other. => ABCD is a parallelogram.