Circles, What Is PI? Learn using rope!

Children use a rope to draw a circle, measure the circumference of the circle, and find the value of Pi.

Circles are all similar, and “the circumference divided by the diameter” produces the same value regardless of their radius. This value is the ratio of the circumference of a circle to its diameter and is called π (Pi). This constant appears in the calculation of the area of a circle and is a type of irrational number known as a transcendental number that can be expressed neither by a fraction nor by any radical sign such as a square root, nor their combination. The number has an infinite number of decimal places, namely, 3.1415926535…, and it has now been computed to 5 trillion decimal places by computers.

The meaning of circumference is the distance around a circle or any curved geometrical shape. It is the one-dimensional linear measurement of the boundary across any two-dimensional circular surface. It follows the same principle behind finding the perimeter of any polygon, which is why calculating the circumference of a circle is also known as the perimeter of a circle.

The circumference of the circle is equal to the length of its boundary. This means that the perimeter of a circle is equal to its circumference. The length of the rope that wraps around the circle’s boundary perfectly will be equal to its circumference. The below-given figure helps you visualize the same. The circumference can be measured by using the given formula:

Circumference of a circle = 2πR =  π D

where ‘r’ is the radius of the circle and π is the mathematical constant whose value is approximated to 3.14 or 22/7. The circumference of a circle can be used to find the area of that circle.

For a circle with radius ‘r’ and circumference ‘C’:

  • π = Circumference/Diameter
  • π = C/2r = C/d
  • C = 2πr


~Prabaharan and Bakiya