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Correction on confusion with triple integral...

• To: mathgroup at smc.vnet.net
• Subject: [mg32488] Correction on confusion with triple integral...
• From: Bradley Stoll <BradleyS at Harker.org>
• Date: Wed, 23 Jan 2002 01:00:08 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

My apologies.  After reading Bob's message I realized I had a typo.  The
limits on r were supposed to be [1/Cos[x],4], not [0,1/Cos[x]].  So, here is
the corrected problem...

Please consider the Integral[r^2Sin[x]drdxdy] with limits as follows:

[0,2Pi]for y, [0,ArcCos[1/4]] for x and [1/Cos[x],4] for r.  Mathematica
returns 27Pi, which is correct.  But, if instead of using ArcCos[1/4], I use
either ArcCos[0.25] or ArcCos[1/4]//N in the limits, Mathematica returns
43Pi.
Any idea why?

• Follow-Ups:
  • Re: Correction on confusion with triple integral...
    • From: Tomas Garza <tgarza01@prodigy.net.mx>