OFFSET
0,1
COMMENTS
Also positive root of arcsin(x) = tan(x).
The equation arcsin(x) = tan(x) has a unique positive root x_0. Note that arcsin(x) < tan(x) for x in [-1, -x_0) U (0, x_0) and arcsin(x) > tan(x) for x in (-x_0, 0) U (x_0, 1].
EXAMPLE
sin(1.5570858155...) = arctan(1.5570858155...) = 0.9999060124...
MATHEMATICA
RealDigits[x /. FindRoot[Tan[x] == ArcSin[x], {x, 0.99}, WorkingPrecision -> 100], 10, 90][[1]] (* Amiram Eldar, Oct 10 2021 *)
PROG
(PARI) solve(x=0.99, 1, tan(x)-asin(x))
CROSSREFS
KEYWORD
nonn,cons
AUTHOR
Jianing Song, Oct 10 2021
STATUS
approved