Search results
Results from the WOW.Com Content Network
In geometry, the circumference (from Latin circumferens, meaning "carrying around") is the perimeter of a circle or ellipse.The circumference is the arc length of the circle, as if it were opened up and straightened out to a line segment. [1]
The area of a regular polygon is half its perimeter multiplied by the distance from its center to its sides, and because the sequence tends to a circle, the corresponding formula–that the area is half the circumference times the radius–namely, A = 1 / 2 × 2πr × r, holds for a circle.
A diameter of an ellipse is any line passing through the centre of the ellipse. [2] Half of any such diameter may be called a semidiameter, although this term is most often a synonym for the radius of a circle or sphere. [3] The longest diameter is called the major axis.
The hydraulic diameter is similarly defined as 4 times the cross-sectional area of a pipe A, divided by its "wetted" perimeter P. For a circular pipe of radius R, at full flow, this is = = as one would expect. This is equivalent to the above definition of the 2D mean diameter.
Since the diameter is twice the radius, the "missing" part of the diameter is (2r − x) in length. Using the fact that one part of one chord times the other part is equal to the same product taken along a chord intersecting the first chord, we find that (2r − x)x = (y / 2) 2. Solving for r, we find the required result.
where r is the radius and d is the diameter of the sphere. Archimedes first derived this formula by showing that the volume inside a sphere is twice the volume between the sphere and the circumscribed cylinder of that sphere (having the height and diameter equal to the diameter of the sphere). [6]
Just as the diameter of a two-dimensional convex set is the largest distance between two parallel lines tangent to and enclosing the set, the width is often defined to be the smallest such distance. Like the diameter, the width can be computed using the method of rotating calipers. [4] The diameter and width are equal only for a body of ...
The number π (/ p aɪ /; spelled out as "pi") is a mathematical constant that is the ratio of a circle's circumference to its diameter, approximately equal to 3.14159.It appears in many formulae across mathematics and physics, and some of these formulae are commonly used for defining π, to avoid relying on the definition of the length of a curve.