Π=C/D, or pi equals the circumference of a given circle divided by that circle’s diameter. This is not an opinion. The name, “pi”, has been used for this ratio for centuries, and it is known that this ratio exists and is constant. The name of this ratio is immaterial. To approximate its value one can use any of many formulas that use series, but these converge very slowly.
So π is inherently in every circle. As I walk from my den to the kitchen, I step along the curvature of the earth which receives light from the sun, and I notice the circles in the washer and dryer doors, the cups and…