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