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semicircle

 
Dictionary: sem·i·cir·cle   (sĕm'ĭ-sûr'kəl) pronunciation
n.
  1. A half of a circle as divided by a diameter.
  2. An object or arrangement of objects or people in the shape of half a circle.
semicircular sem'i·cir'cu·lar (-kyə-lər) adj.

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Veterinary Dictionary: semicircular
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Shaped like a half-circle.

  • s. canals — the passages in the inner ear, in the bony labyrinth concerned with the sense of balance, especially the detection of movement. Each ear has three semicircular canals (anterior, lateral and posterior) situated approximately at right angles to each other. They contain the semicircular ducts.
  • s. ducts — the membranous tubes housed within the semicircular canals.They have enlarged portions at one end, called ampullae, which contain nerve endings, and which are filled with fluid.
  • — The semicircular ducts respond to movement of the head. When the head changes position, the fluid in the duct that lies in the plane of movement also moves but, because of its inertia, the fluid flow lags behind the head movement. Thus the fluid presses against the delicate hairs of the nerves in the ampulla, and these nerves then register the fact that the head is turning in such a direction. — It is the fluid movement in the semicircular ducts that causes the feeling of dizziness or vertigo after spinning. When the spinning stops, the fluid in the horizontal canal continues to move for a moment in the direction of the spin, giving a temporary false reading that the head is turning in the other direction. Motion sickness is caused by the unusual and erratic motions of the head in an airplane, car or ship, and the resulting stimulation of the semicircular ducts. Many animals, even fish, can experience motion sickness.
Word Tutor: semicircle
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pronunciation

IN BRIEF: Half of a round shape.

pronunciation She liked that the moon looked like a semicircle.

Wikipedia: Semicircle
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A semicircle of radius r.

In mathematics (more specifically geometry), a semicircle is a two-dimensional geometric shape that forms half of a circle. Being half of a circle's 360°, the arc of a semicircle always measures 180°. A triangle inscribed in a semicircle is always a right triangle.

Contents

Uses

SemicircleMeans.png

A semicircle can be used to construct arithmetic and geometric means of two lengths using straight-edge and compass. If we make a semicircle with a diameter of a+b, then the length its radius is the arithmetic mean (since it's half of the diameter). The geometric mean can be found by dividing the diameter into two segments of lengths a and b, and then connecting their common end and the semicircle with a segment perpendicular to the diameter. The length of the resulting segment is the geometric mean[1], which can be proved using Pythagorean theorem.

This method can be used to accomplish quadrature of a rectangle (since a square whose sides are equal to geometric mean of sides of a rectangle has the same area as the rectangle), and thus any figure for which we can construct a rectangle with equal area, such as any polygon (but not a circle).

References

  1. ^ Euclid's Elements, Book VI, Proposition 13[1]

See also

External links


Translations: Semicircle
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Dansk (Danish)
n. - halvcirkel

Nederlands (Dutch)
halve cirkel

Français (French)
n. - demi-cercle

Deutsch (German)
n. - Halbkreis

Ελληνική (Greek)
n. - ημικύκλιο

Italiano (Italian)
semicerchio

Português (Portuguese)
n. - semicírculo (m)

Русский (Russian)
полуокружность, полукруг

Español (Spanish)
n. - semicírculo

Svenska (Swedish)
n. - halvcirkel

中文(简体)(Chinese (Simplified))
半圆, 半圆形, 半圆弧

中文(繁體)(Chinese (Traditional))
n. - 半圓, 半圓形, 半圓弧

한국어 (Korean)
n. - 반원형, 반원형의 것

日本語 (Japanese)
n. - 半円, 半円形, 半円形のもの

العربيه (Arabic)
‏(الاسم) نصف دائرة‏

עברית (Hebrew)
n. - ‮חצי-עיגול, חצי-מעגל‬


Best of the Web: semicircle
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Some good "semicircle" pages on the web:


Math
mathworld.wolfram.com
 
 
 
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Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.  Read more
Veterinary Dictionary. Saunders Comprehensive Veterinary Dictionary 3rd Edition. Copyright © 2007 by D.C. Blood, V.P. Studdert and C.C. Gay, Elsevier. All rights reserved.  Read more
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