YSITD_TG_Bot => #ysitd: <licson>: 所以 x = arccos(1/5) = pi / 2 - (1/5 + 1/750 + 1/31250 + 1/1750000 + …) #5746fc4475e9510b040b2cde

YSITD_TG_Bot says to #ysitd

<licson>: 所以 x = arccos(1/5) = pi / 2 - (1/5 + 1/750 + 1/31250 + 1/1750000 + …)

at Thu, May 26, 2016 9:38 PM