Jump to content

Talk:Hypocycloid

Page contents not supported in other languages.
From Wikipedia, the free encyclopedia

Astroids and evolutes/involutes

[edit]

In the article on Evolute, it is claimed that the involute of an evolute of a curve is the original curve again, and that the evolute of an ellipse is an astroid. These together imply that the involute of an astroid is an ellipse.

However, this article claims that the involute of a hypocycloid is a reduced version of the original hypocycloid.

These two statements are in obvious contradiction. Which of the two articles is correct? —Preceding unsigned comment added by 76.253.3.102 (talk) 19:29, 21 November 2010 (UTC)[reply]

Both are technically correct, a curve has only 1 evolute and infinitely many involutes depending on what point you start from. Zamadatix (talk) 17:26, 16 April 2011 (UTC)[reply]

Are the curves circular arcs - Flag of Portland

[edit]

Are the curves, between the cusps, circular arcs (particularly for astroid, k=4)? If yes then can someone provide a reference ? if no then the claim that the flag of Portland, Oregon includes an astroid is false as the referenced city ordinance says it is formed from 4 quarter circles.

Since as k goes to infinity the curve tends to a cycloid it seems likely that the curves are not circular arcs for any k even 4. Astroid doen't claim the curves are circular so perhaps we should say here that the flag contains an astroid-like star. - Rod57 (talk) 10:24, 7 September 2012 (UTC)[reply]

"Smaller circle inside a larger circle"

[edit]

Is it actually part of the definition of a hypocycloid that the rolling circle must be the smaller one? In the case where a larger circle rolls along a smaller circle in its interior, the parametric equations given still produce the correct curve. Would calling that curve a hypocycloid be incorrect? --Ian Maxwell (talk) 01:54, 16 September 2012 (UTC)[reply]

Hypocycloid rolling inside another

[edit]

As shown in the picture, this still applies to the degenerate k=2 hypocycloid. Indeed, the deltoid is the smallest area in which it is possible to continuously rotate a line segment. --81.138.95.57 (talk) 12:32, 24 July 2014 (UTC)[reply]

[edit]

Hello fellow Wikipedians,

I have just modified one external link on Hypocycloid. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:

When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.

This message was posted before February 2018. After February 2018, "External links modified" talk page sections are no longer generated or monitored by InternetArchiveBot. No special action is required regarding these talk page notices, other than regular verification using the archive tool instructions below. Editors have permission to delete these "External links modified" talk page sections if they want to de-clutter talk pages, but see the RfC before doing mass systematic removals. This message is updated dynamically through the template {{source check}} (last update: 5 June 2024).

  • If you have discovered URLs which were erroneously considered dead by the bot, you can report them with this tool.
  • If you found an error with any archives or the URLs themselves, you can fix them with this tool.

Cheers.—InternetArchiveBot (Report bug) 07:09, 14 December 2017 (UTC)[reply]