Search All of the Math Forum:

Views expressed in these public forums are not endorsed by NCTM or The Math Forum.

Notice: We are no longer accepting new posts, but the forums will continue to be readable.

Topic: [ap-calculus] ellipsoid
Replies: 1   Last Post: May 25, 2012 10:26 AM

 Alan Lipp Posts: 1,091 Registered: 12/6/04
RE: [ap-calculus] ellipsoid
Posted: May 25, 2012 10:26 AM

Kevin,

Okay. I think you mean that if you rotate a semi-circle around its diameter you create a sphere, and the method of disks will give the volume of that sphere. If you rotate half an ellipse around one of its axes you produce an ellipsoid and the method of disks will give the volume of this ellipsoid. However, these are special cases. These produce ellipsoids one of whose cross-sections is a circle. The volume of these ellipsoids will be (4/3)pi a b^2 or (4/3) pi a^2 b. The general ellipsoid is not a soid of revolution.

Alan

Alan Lipp
19 Payson Avenue
Easthampton, MA 01026
413-529-3278

The Williston Northampton School inspires students to live with passion, purpose, and integrity.

-----Original Message-----
From: Kevin Regardie [mailto:kregardie@sandi.net]
Sent: Friday, May 25, 2012 9:50 AM
To: AP Calculus
Subject: Re:[ap-calculus] ellipsoid

He's making the connection because when you integrate pi*r^2 using disk method you get volume so in turn he says the integral of pi*ab should give the volume of an ellipsoid. This is his reasoning. I appreciate the responses so far, but no one mentioned the INTEGRAL of area as it relates to volume. Thank you.
====
Course related websites:
http://apcentral.collegeboard.com/calculusab
http://apcentral.collegeboard.com/calculusbc
---
To search the list archives for previous posts go to http://lyris.collegeboard.com/read/?forum=ap-calculus

====
Course related websites:
http://apcentral.collegeboard.com/calculusab
http://apcentral.collegeboard.com/calculusbc
---
To search the list archives for previous posts go to