Question

Write two conditions which are sufficient to ensure that quadrilateral is a rectangle.

Answer 1

If all angles in a quadrilateral are right angles, then it's a rectangle (reverse of the rectangle definition). ... If a parallelogram contains a right angle, then it's a rectangle (neither the reverse of the definition nor the converse of a property).

Answer 2

diagonal bisecting each other.
any two of the adjacent angles are 90 degree