Perimeter - Circumference of A Circle

Circumference of A Circle

The perimeter of a circle, often called circumference, is proportional to its diameter. That is to say, there exists a constant number π (the greek p for perimeter) which gives, if P is the circle's perimeter and D its diameter:

P = π D.

If one knows the radius R of the circle, this formula becomes:

P = 2 π R.

To calculate a circle's perimeter, the knowledge of its radius or diameter and of the number π is sufficient. The problem is that π is not rational (it cannot be expressed as the quotient of two integers), nor algebraic (it is not a root of a polynomial equation with rational coefficients). So, obtaining an accurate approximation of π is not easy. The search for the digits of π mobilizes many fields, such as mathematical analysis, algorithmics and computer science.

Read more about this topic:  Perimeter

Famous quotes containing the words circumference of and/or circle:

    A fact is the end or last issue of spirit. The visible creation is the terminus or the circumference of the invisible world.
    Ralph Waldo Emerson (1803–1882)

    Everything here below beneath the sun is subject to continual change; and perhaps there is nothing which can be called more inconstant than opinion, which turns round in an everlasting circle like the wheel of fortune. He who reaps praise today is overwhelmed with biting censure tomorrow; today we trample under foot the man who tomorrow will be raised far above us.
    —E.T.A.W. (Ernst Theodor Amadeus Wilhelm)