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A332501
Decimal expansion of the number u' in [0,2 Pi] such that the line normal to the graph of y = sin x at (u', sin u') passes through the point (3 Pi/4,0).
2
2, 7, 2, 5, 7, 3, 7, 0, 5, 6, 7, 9, 9, 9, 2, 5, 2, 4, 9, 6, 7, 4, 6, 3, 8, 5, 8, 1, 2, 9, 6, 5, 6, 3, 8, 6, 5, 1, 5, 4, 5, 8, 2, 9, 2, 8, 9, 8, 1, 7, 0, 8, 0, 9, 8, 2, 1, 4, 0, 4, 8, 7, 6, 2, 1, 1, 7, 5, 0, 4, 6, 3, 2, 1, 5, 6, 4, 3, 0, 5, 4, 6, 2, 7, 0, 7
OFFSET
1,1
COMMENTS
Let S and C denote the graphs of y = sin x and y = cos x. For each point (u, sin u) on S, let S(u) be the line normal to S at (u, sin u), and let (snc u, cos(snc u) be the point of intersection of S(u) and C. Let d(u) be the distance from (u,sin u) to (snc u, cos(snc u)). We call d(u) the u-normal distance from S to C and note that in [0,Pi], there is a unique number u' such that d(u') > d(u) for all real numbers u except those of the form u' + k*Pi. We call d(u') the maximal normal distance between sine and cosine, and we call snc the sine-normal-to-cosine function.
The distance from (u',sin u') to its reflection in (3 Pi/4,0) is the maximal normal distance between sine and cosine. This distance is slightly greater than 1. See A332500.
FORMULA
Equals (3/4)*Pi + d/2 = A177870 + A003957/2, where d is the Dottie number. - Gleb Koloskov, Jun 17 2021
EXAMPLE
2.7257370567999252496746385812...
MATHEMATICA
(See A332500.)
PROG
(PARI) 3/4*Pi+solve(x=0, 1, cos(x)-x)/2 \\ Gleb Koloskov, Jun 17 2021
CROSSREFS
KEYWORD
nonn,cons
AUTHOR
Clark Kimberling, May 05 2020
STATUS
approved