avendo usato il fatto che arctan(1) = π/4 e arctan(0)=0.
Appearance in the Putnam Competition==
The evaluation of this integral was the first problem in the [] [[William Lowell Putnam Mathematical Competition|Putnam Competition]]. If it seems trivially routine for a Putnam Competition problem, one may perhaps surmise that its inclusion was motivated by the conjunction of the punch line (summarized by the title of this article) with the fairly nice pattern in the integral itself.
Many years earlier, the result was given in D. P. Dalzell, On 22/7, Journal of the London Mathematical Society 19 ([]) 133-134.
*[[Table of integrals]]
*[[Table of mathematical symbols]]
*[http://www.kalva.demon.co.uk/putnam/putn68.html The problems of the 1968 Putnam competition], with this proof listed as question A1.