about different shapes and irregular object

3. A connected curve that does not cross itself and ends at the same
point where it begins is known as simple closed curve. In
mathematics, a curve (also called a curved line in older texts) is,
generally speaking, an object similar to a line but which is not
required to be straight. E.g. : Circle, Ellipses, this table, etc.

4. The rectangle, like the square, is one of the most
commonly known quadrilaterals. It is defined as
having all four interior angles 90° (right angles).
 Opposite sides are parallel.
 The diagonals bisect each other.

5. It has 4 lines equal in
length.
The Angles opposite each
other are equal in size.
The diagonals intersect at
90 degrees
It is a Simple
Quadrilateral (The sum of
its angles is 360 degrees)

6. In geometry, a pentagon is any five-sided
polygon. A pentagon may be simple or self-
intersecting. The sum of the internal angles in
a simple pentagon is 540°. A pentagram is an
example of a self-intersecting pentagon.

7. In mathematics(more
specifically geometry), a
semicircle is a two-
dimensional geometric shape
that forms half of a circle.
Being half of a circle's 360°,
the arc of a semicircle always
measures 180° or a half turn