cone

The volume and surface area of a cone are given by formulae involving a few simple dimensions.

In geometry, a pyramid with a circular base. If the point (vertex) is directly above the centre of the circle, it is known as a right circular cone. The volume (V) of this cone is given by the formula V = 1/3πr²h where h is the perpendicular height and r is the base radius.

A right circular cone is generated by rotating an isosceles triangle about its line of symmetry. The distance from the edge of the base of a cone to the vertex is called the slant height. In a right circular cone of slant height l, the curved surface area is πrl, and the area of the base is πr². Therefore the total surface area A = πrl + πr² = πr(l + r).

For example, to find the volume and surface area of a cone with a perpendicular height of 4 cm and radius of 3 cm:

Volume = 1/3πr²h, so

V = 1/3π × 3² × 4

V = 37.7 cm³ (to 1 decimal place)

Surface area = πr(l + r). First the slant length (l) is calculated:

Using Pythagoras' theorem,

l² = h² + r², so

l² = 4² + 3² = 16 + 9 = 25, so

l = 5 cm

The surface area can now be calculated:

A = πr(l + r), so

A = π × 3(3 + 5) = 3π × 8 = 24π, so

A = 75.4 cm² (to 1 decimal place)

cone

In botany, the reproductive structure of the conifers and cycads; also known as a strobilus. It consists of a central axis surrounded by numerous, overlapping, scalelike, modified leaves (sporophylls) that bear the reproductive organs. Usually there are separate male and female cones, the former bearing pollen sacs containing pollen grains, and the larger female cones bearing the ovules that contain the ova or egg cells. The pollen is carried from male to female cones by the wind (anemophily). The seeds develop within the female cone and are released as the scales open in dry atmospheric conditions, which favour seed dispersal.

In some groups (for example, the pines) the cones take two or even three years to reach maturity. The cones of junipers have fleshy cone scales that fuse to form a berrylike structure. One group of angiosperms, the alders, also bear conelike structures; these are the woody remains of the short female catkins, and they contain the alder fruits.

cone

In zoology, type of light-sensitive cell found in the retina of the eye.

Cone (1870–1949)

US art collectors. Claribel Cone (1864–1929) and Etta Cone (1870–1949) were sisters who established an artistic salon and began collecting antiques, textiles, and modern paintings. The sisters amassed an impressive collection of modern and contemporary French art.

They were both born in Jonesboro, Tennessee. Their family moved to Baltimore (c. 1870), and their brothers founded the Cone Mills, a textile business. The sisters studied locally, and Claribel attended the Woman's Medical College of Baltimore, Maryland, then worked in the pathology laboratory of the newly founded Johns Hopkins Medical School 1894–1903. They were friends of Gertrude and Leo Stein, who briefly lived in Baltimore in 1891, and the sisters became frequent guests of the Steins in France. After both sisters died, their funds and collection were bequeathed to the Baltimore Museum of Art.