Answer:
Square: A square is a quadrilateral with four equal sides and four right angles.
Rhombus: A rhombus is a quadrilateral with four equal sides, but the angles are not necessarily right.
Rectangle: A rectangle is a quadrilateral with four right angles, but opposite sides can be different lengths.
Since the square is both a rhombus and a rectangle, this means that it has both the properties of a rhombus (equal sides) and those of a rectangle (right angles). Thus, all features of a rectangle are filled by a square, including equal sides. So a rhombus that has equal sides, by definition, is also a rectangle, because it has four right angles.
Explanation: