Origin of cardioid

Classical Greek*kardioeid?s*, heart-shaped from

*kardia*, heart +

*-oeid?s*, -oid

Math. a curve more or less in the shape of a heart, traced by a point on the circumference of a circle that rolls around the circumference of another equal circle

Origin of cardioid

Classical GreekWebster's New World College Dictionary, Fifth Edition Copyright © 2014 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

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"cardioid." YourDictionary, n.d. Web. 15 January 2019. <https://www.yourdictionary.com/cardioid>.

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cardioid. (n.d.). Retrieved January 15th, 2019, from https://www.yourdictionary.com/cardioid

noun

A heart-shaped plane curve, the locus of a fixed point on a circle that rolls on the circumference of another circle with the same radius.

**cardioid**

The parametric equations of this cardioid are

x = -a cos &thgr; (1 - cos &thgr;),

y = a sin &thgr; (1 - cos &thgr;).

THE AMERICAN HERITAGE® DICTIONARY OF THE ENGLISH LANGUAGE, FIFTH EDITION by the Editors of the American Heritage Dictionaries. Copyright © 2016, 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

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**MLA Style**

"cardioid." YourDictionary, n.d. Web. 15 January 2019. <https://www.yourdictionary.com/cardioid>.

**APA Style**

cardioid. (n.d.). Retrieved January 15th, 2019, from https://www.yourdictionary.com/cardioid

A heart-shaped plane curve, the locus of a fixed point on a circle that rolls on the circumference of another circle with the same radius.

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"cardioid." YourDictionary, n.d. Web. 15 January 2019. <https://www.yourdictionary.com/cardioid>.

**APA Style**

cardioid. (n.d.). Retrieved January 15th, 2019, from https://www.yourdictionary.com/cardioid

Noun

(*plural* cardioids)

- (geometry) An epicycloid with exactly one cusp; the plane curve with polar equation - having a shape supposedly heart-shaped

Adjective

(*comparative* more cardioid, *superlative* most cardioid)

- Having this characteristic shape

Origin

*cardio-* + *-oid*

English Wiktionary. Available under CC-BY-SA license.

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**MLA Style**

"cardioid." YourDictionary, n.d. Web. 15 January 2019. <https://www.yourdictionary.com/cardioid>.

**APA Style**

cardioid. (n.d.). Retrieved January 15th, 2019, from https://www.yourdictionary.com/cardioid

- The combination of rays is also sufficient in practice if the
**cardioid**surface is replaced, by a spherical one. - The polar equation to the
**cardioid**is r=a(1-}-cos 0). - The form of the limacon depends on the ratio of the two constants; if a be greater than b, the curve lies entirely outside the circle; if a equals b, it is known as a
**cardioid**; if a is less than b, the curve has a node within the circle; the particular case when b= 2a is known as the trisectrix. - In the figure (1) is a limagon, (2) the
**cardioid**, (3) the trisectrix. - The epicychid when the radii of the circles are equal is the
**cardioid**(q.v), and the corresponding trochoidal curves are limacons.

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