Perimeter and Area

The length of the boundary of a closed region is called its perimeter. Perimeter of any regular polygon with n sides is equal to n × (length of a side).

Perimeter of a quadrilateral with sides measuring a, b, c and d is equal to a + b + c + d.

Perimeter of a rectangle = 2(length + breadth)

Perimeter of a square = 4 × length of each side

Perimeter of a triangle is equal to the sum of its all three sides.

Perimeter of a parallelogram with two opposite sides measuring a and b is equal to 2(a + b). Area of any regular polygon is the amount of the surface (region) enclosed by its boundary.

Area of a rectangle = length × breadth

Area of a square = (Side)2

Area of a parallelogram with base a and height b is equal to (a × b).

Triangles formed in a rectangle are exact copies of each other therefore they are congruent. Hence, equal in area.

Area of each triangle = (1/2) × base × height

When we cut the diagonal of a square we get four congruent triangles. Area of each triangle = (1/4) × area of square

Circumference is a kind of perimeter. It is the distance around a circular region.

Circumference of a circle = πd = 2πr, where d is the diameter and r is the radius of the circle.

Area of a circle = πr2, where r is the radius of the circle.

Conversion of units is the conversion between different units of measurement for the same quantity, typically through multiplicative conversion factors.

For example: 1 hectare = 104 m2

Area of rectangular path = Area of outer rectangle – Area of inner rectangle