1.
 Perimeter:
The length of the boundary of a closed figure
is called the perimeter of the plane figure.
The units of perimeter are same as that of
length, i.e., m, cm, mm, etc.

2.
 Area:
The area is the region bounded by the shape
of an object. The space covered by the figure
or any two-dimensional geometric shape, in a
plane, is the area of the shape.
Area is measured in square units (m2, cm2,
in2, etc.)

3.
Perimeter and Area of a Rectangle
 A rectangle is a figure/shape
with opposite sides equal and
all angles equal to 90 degrees.
The area of the rectangle is the
space covered by it in an XY plane.

Perimeter of a Rectangle = 2(a+b)

Area of Rectangle = a × b
where a and b are the length and width of the
rectangle.

4.
Perimeter and Area of a Square
 A Square is a figure/shape
with all four sides equal and
all angles equal to 90 degrees.
The area of the square is the
space occupied by the square
in a 2D plane and its perimeter
is the distance covered on the outer line.
 Perimeter of a Square = 4a
 Area of a Square = a2

5.
 Perimeter and Area of a Triangle
 The triangle has three sides. Therefore,
the perimeter of any given triangle,
whether it is scalene, isosceles or
equilateral, will be equal to the sum of the
length of all three sides.
And the area of any triangle is the space occupied by it in a plane.

Perimeter of a triangle = a + b +c , where a, b and c are the
three different sides of the triangle.

Area of a triangle = 1/2 b × h; where b is the base and h is
the height of the triangle.