arctanx+arctan（1/x）=?已知x＞0.
问题描述：
arctanx+arctan（1/x）=?已知x＞0.
答
let
tana = x
then arctanx = a
cota = 1/x
arctan(1/x) = 90°-a
arctanx+arctan（1/x）= 90°