OFFSET
1,1
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..5000
FORMULA
Equals Pi - arcsin(sqrt(3/5)) = Pi - arctan(sqrt(3/2)). - Amiram Eldar, Jul 08 2023
EXAMPLE
arccos(-sqrt(2/5)) = 2.25551552979717...
MATHEMATICA
r = Sqrt[1/5]; s = Sqrt[2/5];
N[ArcSin[r], 100]
RealDigits[%] (* A073000 *)
N[ArcCos[r], 100]
RealDigits[%] (* A105199 *)
N[ArcTan[r], 100]
RealDigits[%] (* A188595 *)
N[ArcCos[-r], 100]
RealDigits[%] (* A137218 *)
N[ArcSin[s], 100]
RealDigits[%] (* A195701 *)
N[ArcCos[s], 100]
RealDigits[%] (* A195708 *)
N[ArcTan[s], 100]
RealDigits[%] (* A195709 *)
N[ArcCos[-s], 100]
RealDigits[%] (* A195710 *)
RealDigits[ArcCos[-Sqrt[(2/5)]], 10, 120][[1]] (* Harvey P. Dale, Apr 06 2023 *)
PROG
(PARI) acos(-sqrt(2/5)) \\ G. C. Greubel, Nov 18 2017
(Magma) [Arccos(-Sqrt(2/5))]; // G. C. Greubel, Nov 18 2017
CROSSREFS
KEYWORD
nonn,cons
AUTHOR
Clark Kimberling, Sep 23 2011
STATUS
approved