In Hyperbolic Geometry, rectangles do not exist, and, therefore, neither do squares. In Hyperbolic Geometry, if a quadrilateral has 3 right angles, then the forth angle must be acute. Construct an example of this. The following is a list of theorems in Euclidean Geometry. It is possible to construct a Regular Quadrilateral.
All regular quadrilaterals have four right angles.
The two lines passing through the midpoints of the opposite sides of a regular quadrilateral divide the regular quadrilateral into four smaller regular quadrilaterals. The diagonals of a regular quadrilateral bisect each other. The diagonals of a regular quadrilateral are perpendicular. A Parallelogram is a quadrilateral in which the opposite sides are parallel. The following is a list of theorems about Parallelograms in Euclidean Geometry.