Question

The quadrilateral that Ye Li drew is a square. It has the following properties:
All angles are 90 degrees (rectangle property).
All sides are equal in length (rhombus property).
Opposite sides are equal and parallel (both rectangle and rhombus properties)

Answer 1

Yes — that description defines a square.

Reason: a square is exactly a quadrilateral that is both a rectangle and a rhombus. A rectangle gives the four right angles; a rhombus gives four equal sides. Together those two facts mean all four sides are equal and all four angles are 90°, which is the definition of a square. Opposite sides being equal and parallel follows from either the rectangle or rhombus properties.

Additional immediate consequences:
- Diagonals bisect each other.
- Diagonals are equal in length (rectangle property) and perpendicular to each other (rhombus property), so here the diagonals are equal and perpendicular and they bisect the interior angles.
- Area = side^2; perimeter = 4 × side.