1. The problem asks: What is a rectangle? 2. A rectangle is a type of quadrilateral (a four-sided polygon) where all interior angles are right angles (each measuring 90 degrees). 3. Important properties of a rectangle include: - Opposite sides are parallel and equal in length. - All angles are equal to 90 degrees. - The diagonals are equal in length and bisect each other. 4. The formula for the area of a rectangle is: $$\text{Area} = \text{length} \times \text{width}$$ 5. The formula for the perimeter of a rectangle is: $$\text{Perimeter} = 2 \times (\text{length} + \text{width})$$ 6. Rectangles are special cases of parallelograms and squares (a square is a rectangle with all sides equal). This explanation covers the definition and key properties of a rectangle.