a rhombus
square
Rhombus!
a pentagon
rhombus. The rhombus is a quadrilateral with all sides equal in length. It is also a parallelogram, so opposite sides are parallel and equal in length, and opposite angles are equal.
A square
A Rectangle.
a square
Any parallelogram, including rhombus, but not including rectangle or square.
rectangle
Opposite sides are of equal length and parallel. The four angles are all right-angles (90 degrees( .
A parallelogram always has opposite sides of equal length. Its 4 angles may be right angles, but in most parallelograms they're not. If they are, then that parallelogram is also called a 'rectangle'.
rhombus