Envelope

Pronunciation: /ˈɛn.vəˌloʊp/ Explain

Figure 1: Creation of an envelope.

In mathematics, an envelope is a curve that is tangent to a family of lines or other geometric shapes. Figure 1 shows the creation of an envelope from a family of lines. Manipulative 1 shows two blue lines that are envelopes for a family of circles. Click on the blue points and drag them to change the figure. What would the circles look like if the two blue envelope lines were concurrent? Manipulative 1 - Envelope of Circles Created with GeoGebra.

References

1. McAdams, David E.. All Math Words Dictionary, envelope. 2nd Classroom edition 20150108-4799968. pg 70. Life is a Story Problem LLC. January 8, 2015. Buy the book

Cite this article as:

McAdams, David E. Envelope. 3/11/2019. All Math Words Encyclopedia. Life is a Story Problem LLC. http://www.allmathwords.org/en/e/envelope.html.

Image Credits

• All images and manipulatives are by David McAdams unless otherwise stated. All images by David McAdams are Copyright © Life is a Story Problem LLC and are licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.
• Envelope of Curves: Sam Derbyshire, https://en.wikipedia.org. Licensed under the terms of the GNU Free Documentation License, Version 1.2 or any later version. https://en.wikipedia.org/wiki/File:EnvelopeAnim.gif.

Revision History

12/21/2018: Reviewed and corrected IPA pronunication. (McAdams, David E.)
7/5/2018: Removed broken links, updated license, implemented new markup, implemented new Geogebra protocol. (McAdams, David E.)
1/24/2010: Added "References". (McAdams, David E.)
11/18/2008: Changed manipulative to GeoGebra. (McAdams, David E.)
5/10/2008: Initial version. (McAdams, David E.)