YSITD_TG_Bot => #ysitd: <licson>: 所以 x = arccos(1/5) = pi / 2 - (1/5 + 125/6 + 3125/10 + 1171875/336 + …) #5746884f75e9510b040b22c6

YSITD_TG_Bot says to #ysitd

<licson>: 所以 x = arccos(1/5) = pi / 2 - (1/5 + 125/6 + 3125/10 + 1171875/336 + …)

at Thu, May 26, 2016 1:23 PM