In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid for the diameter of a sphere. The word "diameter" is derived from Greek language διάμετρος ( diametros), "diameter of a circle", from δια- ( dia-), "across, through" μέτρον ( metron), "measure". Online Etymology Dictionary It is often abbreviated ..
Cattle (colloquially cows) are the most common type of large domesticated ungulates. They are a prominent modern member of the subfamily Bovinae, are the most widespread species of the genus Bos, and are most commonly classified collectively as Bos primigenius. Cattle are raised as livestock for meat (beef and veal), as dairy animals for milk and other , and as draft animals ( or bullocks) (pulling , and the like). Other products include leather and dung for manure or fuel. In some regions, such as p..
The narwhal, or narwhale ( Monodon monoceros), is a medium-sized toothed whale that possesses a large "tusk" from a protruding canine tooth. It lives year-round in the Arctic waters around Greenland, Canada, and Russia. It is one of two living species of whale in the Monodontidae family, along with the beluga whale. The narwhal males are distinguished by a long, straight, helical tusk, which is an elongated upper left canine. The narwhal was one of many species described by Carl Linnaeus in his publicatio..
The monarch butterfly or simply monarch ( Danaus plexippus) is a milkweed butterfly (subfamily Danainae) in the family Nymphalidae. Other common names depending on region include milkweed, common tiger, wanderer, and black veined brown. It may be the most familiar North American butterfly, and is considered an iconic pollinator species. Its wings feature an easily recognizable black, orange, and white pattern, with a wingspan of The viceroy butterfly is similar in color and pattern, but is markedly ..
Igneous rock (derived from the Latin word ignis meaning fire) is one of the three main rock types, the others being sedimentary and metamorphic rock. Igneous rock is formed through the cooling and solidification of magma or lava. Igneous rock may form with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks. This magma can be derived from partial melts of pre-existing rocks in either a planet's mantle or crust. Typically, the me..
