<?xml version="1.0" encoding="utf-8" standalone="yes"?><rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom"><channel><title>Geometry on dasarpAI</title><link>https://dasarpai.com/tags/geometry/</link><description>Recent content in Geometry on dasarpAI</description><generator>Hugo -- gohugo.io</generator><language>en</language><managingEditor>hari@dasarpai.com (Dr. Hari Thapliyaal)</managingEditor><webMaster>hari@dasarpai.com (Dr. Hari Thapliyaal)</webMaster><copyright>© 2026 Dr. Hari Thapliyaal</copyright><lastBuildDate>Mon, 24 Aug 2026 00:00:00 +0000</lastBuildDate><atom:link href="https://dasarpai.com/tags/geometry/index.xml" rel="self" type="application/rss+xml"/><item><title>Conic Sections and Their 3D Shapes — Circles, Ellipses, Parabolas, and Hyperbolas in Two and Three Dimensions</title><link>https://dasarpai.com/dsblog/conic-sections-and-their-3d-shapes/</link><pubDate>Mon, 24 Aug 2026 00:00:00 +0000</pubDate><author>hari@dasarpai.com (Dr. Hari Thapliyaal)</author><guid>https://dasarpai.com/dsblog/conic-sections-and-their-3d-shapes/</guid><description>&lt;p>
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&lt;img class="my-0 rounded-md" loading="lazy" src="https://dasarpai.com/assets/images/dspost/dsp6312-conic-sections-and-3d-shapes.jpg" alt="Conic Sections and Their 3D Shapes" />
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&lt;h1 class="relative group">Conic Sections and Their 3D Shapes
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&lt;h2 class="relative group">Circles, ellipses, parabolas, and hyperbolas in two and three dimensions
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&lt;p>A circle is not an isolated shape. It is the simplest member of a family: rotate it around an axis and you get a &lt;strong>sphere&lt;/strong>; slide the same cross-section along a straight line and you get a &lt;strong>cylinder&lt;/strong>. The same pattern repeats for &lt;strong>ellipses&lt;/strong>, &lt;strong>parabolas&lt;/strong>, and &lt;strong>hyperbolas&lt;/strong> — each 2D curve has a natural 3D &lt;strong>surface of revolution&lt;/strong> and a natural &lt;strong>cylindrical extrusion&lt;/strong>.&lt;/p>
&lt;p>This article is a shape-and-formula guide. For each family you get:&lt;/p>
&lt;ul>
&lt;li>the standard equation in the plane,&lt;/li>
&lt;li>the 3D surface you obtain by rotation,&lt;/li>
&lt;li>the 3D surface you obtain by extrusion along the \(z\)-axis,&lt;/li>
&lt;li>&lt;strong>everyday names&lt;/strong> so you can connect the formula to objects you already know,&lt;/li>
&lt;li>a labeled illustration to fix the picture in memory.&lt;/li>
&lt;/ul>
&lt;p>We work in Cartesian coordinates \((x,y)\) in the plane and \((x,y,z)\) in space. Parameters \(a,b,c,p,r>0\) unless noted otherwise.&lt;/p></description></item></channel></rss>