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A235509 Decimal expansion of arccos(4/5). 1
6, 4, 3, 5, 0, 1, 1, 0, 8, 7, 9, 3, 2, 8, 4, 3, 8, 6, 8, 0, 2, 8, 0, 9, 2, 2, 8, 7, 1, 7, 3, 2, 2, 6, 3, 8, 0, 4, 1, 5, 1, 0, 5, 9, 1, 1, 1, 5, 3, 1, 2, 3, 8, 2, 8, 6, 5, 6, 0, 6, 1, 1, 8, 7, 1, 3, 5, 1, 2, 4, 7, 4, 8, 1, 1, 6, 2, 1, 0, 8, 8, 7, 1, 2, 8, 1, 6, 8, 4, 4, 7, 0, 1, 2, 8, 2, 7, 4, 8, 8 (list; constant; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Given a square ABCD, there is one point M equidistant from A, B and the middle of CD. The measure of the angle BAM is arccos(4/5) (or arcsec(5/4)). This angle is the smallest angle of the well-known (3, 4, 5) Pythagorean triangle.

Also the polar angle phi of the viewing cone that cuts out exactly 10% of the celestial sphere; phi = arccos(1-2f), where f is the cut-out fraction of the full solid angle. - Stanislav Sykora, Feb 14 2016

LINKS

Table of n, a(n) for n=0..99.

Jean-François Alcover, Figure showing square ABCD and angle BAM

FORMULA

Cos(A235509) + cos(A195771) = 1.

EXAMPLE

0.64350110879328438680280922871732263804151059111531238286560611871351...

In degrees: 36.869897645844...°

MATHEMATICA

RealDigits[ArcCos[4/5], 10, 100] // First

CROSSREFS

Cf. A195771.

Sequence in context: A182618 A118227 A199429 * A224927 A200104 A154747

Adjacent sequences:  A235506 A235507 A235508 * A235510 A235511 A235512

KEYWORD

nonn,cons

AUTHOR

Jean-François Alcover, Jan 14 2014

STATUS

approved

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Last modified June 25 18:15 EDT 2017. Contains 288729 sequences.