Mensuration:

Mensuration is the branch of mathematics which concerns itself with the measurement of Lengths, areas & volume of different geometrical shapes or figures.

Plane Figure:A figure which lies in a plane is called a plane figure.

For e.g: a rectangle, square, a rhombus, a parallelogram, a trapezium.

Perimeter:

The perimeter of a closed plane figure is the total length of its boundary.

In case of a triangle or a polygon the perimeter is the sum of the length of its sides.

Unit of perimeter is a centimetre (cm), metre(m) kilometre(km) e.t.c

Area:The area of the plane figure is the measure of the surface enclose by its boundary.

The area of a triangle are a polygon is the measure of the surface enclosed by its sides.

A square centimetre (cm²) is generally taken at the standard unit of an area. We use square metre (m²) also for the units of area.

Circumference of a circle is the perimeterof a circle.

In a circle the radius is half of thediameter.

The approximate value of π( Pi) is= 22/7