Talk:Cardioid

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WikiProject Mathematics
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This article is within the scope of WikiProject Mathematics, which collaborates on articles related to mathematics.
Mathematics rating: Start Class Low Priority  Field: Geometry

Move the graph to the top?

- seconded


Huh?? Why move a chunk of page content off to a subpage? Dysprosia 01:27, 19 May 2005 (UTC)

See Wikipedia:WikiProject Mathematics/Proofs#Cardioid. -- Jitse Niesen 11:33, 19 May 2005 (UTC)

Contents

[edit] Pear?

I'm no geometer, but it looks like the cross-section of a globe tomato to me.


It's a butt... —Preceding unsigned comment added by 84.238.88.87 (talk) 08:49, 12 January 2008 (UTC)

[edit] Images

I do not understand how the images can be understood - what are x and y? --Abdull 16:11, 23 May 2006 (UTC)

The Equations section describes x and y in terms of theta. --Jevon 20:39, 25 May 2006 (UTC)
The equations express the rectangular coordinates of the curve, x and y, in terms of a parameter theta. That is, for each value of theta, compute x(theta) and y(theta), and plot the point (x,y) measured x units to the right of the y axis, and y units above the x axis (other direction for negatives). The set of all such points makes the curve shown in the image. So, x and y are just numbers to describe the location of a point on a curve. Dicklyon 22:25, 5 June 2006 (UTC)
The other way to understand the images is to ignore x and y, and just look at rho (radius) and theta. At each angle theta measured from the positive x axis, compute the radius rho and put a point that far from the origin. At 180 degrees, the formula 1+cos(theta) gives zero, so you get a point at the origin, which is the cusp. By displacing theta, or using sin instead of cosine, the whole picture just rotates around that cusp. Dicklyon 22:29, 5 June 2006 (UTC)

[edit] IMHO should be merged with into Heart (Symbol)

IMHO should be merged with into Heart (Symbol) --Wulf 03:17, 5 June 2006 (UTC)

Absolutely not. Read the article. The two shapes are not the same. Dysprosia 03:23, 5 June 2006 (UTC)

That's almost as bad as calling a trapezoid a squashed square. --ssd 07:14, 26 August 2007 (UTC)

[edit] The caustic seen at the bottom of a coffee cup

It's a nephroid. I have solved this problem. —Preceding unsigned comment added by 84.2.80.109 (talk) 11:49, 29 October 2007 (UTC)

As the article states, it may be a cardioid, and it may be a nephroid. It depends on the angle of the light rays relative to the bottom of the cup. Cheers, Doctormatt 17:58, 29 October 2007 (UTC)