The following integral,
\int_0^1 \frac{x^4(1-x)^4}{x^2 + 1} \mathrm{d}x = \frac{22}{7} – \pi
is clearly positive, which proves that \pi < 22/7.
Is there a similar integral which proves \pi > 333/106?
Answer
This integral would do the job:
\int_0^1 \frac{x^5(1-x)^6(197+462x^2)}{530(1+x^2)}\:dx= \pi -\frac{333}{106}
Also you can refer to S.K. Lucas Integral proofs that 355/113 > \pi, Gazette, Aust. Math. Soc. 32 (2005), 263-266.
This is the link. (Thanks to lhf for pointing out.)
Attribution
Source : Link , Question Author : Community , Answer Author : Community