Re: confusion with triple integral...

*To*: mathgroup at smc.vnet.net*Subject*: [mg32485] Re: confusion with triple integral...*From*: "Dave Snead" <dsnead6 at charter.net>*Date*: Wed, 23 Jan 2002 01:00:03 -0500 (EST)*References*: <a2j8o9$79j$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Bradley Stoll <BradleyS at harker.org> wrote in message news:a2j8o9$79j$1 at smc.vnet.net... > Please consider the Integral[r^2Sin[x]drdxdy] with limits as follows: > [0,2Pi]for y, [0,ArcCos[1/4]] for x and [0,1/Cos[x]] 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?j > > Bradley Stoll > San Jose, CA > I get a consistent 5 Pi for both these cases In[3]:= Integrate[r^2Sin[x],{y,0,2 Pi},{x,0,ArcCos[1/4]},{r,0,1/Cos[x]}] Out[3]= 5 \[Pi] In[4]:= Integrate[r^2Sin[x],{y,0,2 Pi},{x,0,ArcCos[.25]},{r,0,1/Cos[x]}] Out[4]= 15.708 -- Dave Snead