Q.Why is it called a decagon?
A.Because it has ten sides and ten angles, and there are both regular and irregular decagons.
_Rect-angle or Oblong_.
Q.What is this?
A.A rectangle or oblong.

Q.How many sides and angles has it?
A.Four, the same as a square.

Q.What is the difference between a rectangle and a square?
A.A rectangle has two long sides, and the other two are much shorter, but a square has its sides equal.
_Rhomb_.
Q.What is this?
A.A rhomb.

Q.What is the difference between a rhomb and a rectangle?
A.The sides of the rhomb are equal, but the sides of the rectangle are not all equal.

Q.Is there any other difference?
A.
Yes, the angles of the rectangle are equal, but the rhomb has only its opposite angles equal.
_Rhomboid_.
Q.What is this?
A.A rhomboid.