The study of geometry can be divided into two types: Plane Geometry and
Solid Geometry. Plane geometry deals with only two dimensions figures
like line, rectangle, square, circle and triangle whereas solid geometry
deals with 3D figures like cube, cuboid, cone and cylinder. Plane
geometry contains the shapes has length and width. These figures can be
drawn on a sheet of paper.
Figures mentioned above are
flat and can only be drawn on paper or 2D sheet. They have two
dimensions: length and breadth. Plane geometry figures are classified by
their angles and shapes.
Properties of some plane figures:

Square is a 4
sided figure with same length and four 90$^o$ angles.

Triangle is a 3
sided figure with three straight sides and three angles.

Circle is a round flat figure.

Rhombus is 4 sided shape with parallel opposite sides and all the sides are the same length.
There are a number of formulas in Plane Geometry to calculate measures like area and perimeter.
Below are some formulas used in plane geometry: