From: nma@12000.org   
      
   On 9/28/2015 4:35 PM, clicliclic@freenet.de wrote:   
      
   >> Mathematica 10.1 and Maple 15 return unevaluated.   
   >>   
   >   
   > But the Wolfram integrator can still do it! Mathematica is evidently   
   > entering its second childhood.   
   >   
   > Martin.   
   >   
      
   In this case, the online version might be using the newer   
   kernel. I am using 10.1, and Mathematica is now at 10.2   
   officially (released July 14). I have not updated yet myself,   
   waiting for version 11.   
      
   $Version   
   Out[38]= "10.1.0  for Microsoft Windows (64-bit) (March 24, 2015)"   
      
   Integrate[ArcCos[x^2 - Sqrt[1 - x^2]], x]   
   Out[39]= Integrate[ArcCos[x^2 - Sqrt[1 - x^2]], x]   
      
   --Nasser   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)