## Thursday, May 4, 2023

### Geometry - Calculation - Circle !!

2 x radius : how to calculate dia or circumference !!

A circle is a shape consisting of all points in a plane that are at a given distance from a given point, the centre. Equivalently, it is the curve traced out by a point that moves in a plane so that its distance from a given point is constant.

Specifically, a circle is a simple closed curve that divides the plane into two regions: an interior and an exterior.  In Maths or Geometry, a circle is a special kind of ellipse in which the eccentricity is zero and the two foci are coincident.  A circle is a basic 2D shape which is measured in terms of its radius.

The circumference of a circle is the perimeter of the circle. It is the total length of the boundary of the circle. The circumference of a circle is the product of the constant π and the diameter of the circle. A person walking across a circular park, or a circular table to be bordered requires this metric of the circumference of a circle. The circumference is a linear value and its units are the same as the units of length.

The distance between any point of the circle and the centre is called the radius. Usually, the radius is required to be a positive number. The distance from the centre of the circle to the outer line is its radius. Diameter is the line which divides the circle into two equal parts and is also equal to twice of the radius.  In other words, the diameter of a circle is the line that passes through the center and divides the circle into two equal parts.

Forget all the above – this  cow for sure would not know the formula or Science or rationale but was crossing the beautiful kolam at Thiruvallikkeni – photo of kolam and its makers.