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A231986 Decimal expansion of the solid angle (in steradians) subtended by a spherical square of one radian side. 8

%I

%S 9,2,7,6,8,9,4,7,5,3,2,2,3,1,3,6,4,0,7,9,5,6,1,3,2,3,8,1,4,5,9,5,4,9,

%T 1,7,6,3,0,4,0,4,0,0,6,4,2,4,5,7,4,3,4,0,8,9,9,9,8,6,9,0,4,6,6,9,1,7,

%U 4,8,6,1,8,8,5,9,1,4,5,1,8,8,9,3,9,3,7,1,3,1,0,9,9,0,3,1,9,1,2,3,5,3,9,4,4

%N Decimal expansion of the solid angle (in steradians) subtended by a spherical square of one radian side.

%C In spherical geometry, the solid angle (in steradians) covered by a rectangle with arc-length sides r and s (in radians) equals Omega = 4*arcsin(sin(s/2)*sin(r/2)). For this constant, r = s = 1.

%C Note: It is a common mistake to think that 1 radian squared gives one steradian! See also the discussion in A231984.

%D G. V. Brummelen, Heavenly Mathematics: The Forgotten Art of Spherical Trigonometry, Princeton University Press, 2012, ISBN 978-0691148922.

%H Stanislav Sykora, <a href="/A231986/b231986.txt">Table of n, a(n) for n = 0..2000</a>

%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Solid_angle#Pyramid">Solid angle</a>, Section 3.3 (Pyramid)

%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Steradian">Steradian</a>

%F 4*arcsin(sin(1/2)^2).

%e 0.9276894753223136407956132381459549176304040064245743408999869...

%Y Cf. A072097 (rad/deg), A019685 (deg/rad), A231981 (sr/deg^2), A231982 (deg^2/sr), A231987 (inverse problem).

%K nonn,cons,easy

%O 0,1

%A _Stanislav Sykora_, Nov 17 2013

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Last modified January 21 02:59 EST 2019. Contains 319344 sequences. (Running on oeis4.)