A197138 Decimal expansion of the x-intercept of the shortest segment from the x axis through (3,2) to the line y=x.

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

Offset

1,1

Comments

The shortest segment from one side of an angle T through a point P inside T is called the Philo line of P in T. For discussions and guides to related sequences, see A197032, A197008 and A195284.

Links

Table of n, a(n) for n=1..81.

Example

length of Philo line:   2.886117...; see A197139
endpoint on x axis:   (3.4883, 0)
endpoint on line y=x: (2.80376, 2.80376)

Mathematica

f[t_] := (t - k*t/(k + m*t - m*h))^2 + (m*k*t/(k + m*t - m*h))^2;
g[t_] := D[f[t], t]; Factor[g[t]]
p[t_] :=  h^2 k + k^3 - h^3 m - h k^2 m - 3 h k t + 3 h^2 m t + 2 k t^2 - 3 h m t^2 + m t^3
m = 1; h = 3; k = 2; (* slope m; point (h, k) *)
t = t1 /. FindRoot[p[t1] == 0, {t1, 1, 2}, WorkingPrecision -> 100]
RealDigits[t]  (* A197138 *)
{N[t], 0} (* endpoint on x axis *)
{N[k*t/(k + m*t - m*h)],
N[m*k*t/(k + m*t - m*h)]} (* endpoint on line y=x *)
d = N[Sqrt[f[t]], 100]
RealDigits[d]  (* A197139 *)
Show[Plot[{k*(x - t)/(h - t), m*x}, {x, 0, 4}],
ContourPlot[(x - h)^2 + (y - k)^2 == .003, {x, 0, 4}, {y, 0, 3}],
PlotRange -> {0, 3}, AspectRatio -> Automatic]

Crossrefs

Cf. A197032, A197139, A197008, A195284.

Sequence in context: A310015 A123323 A034772 * A065309 A097689 A349609

Adjacent sequences: A197135 A197136 A197137 * A197139 A197140 A197141

Keyword

nonn,cons

Author

Clark Kimberling, Oct 10 2011

Extensions

Incorrect trailing digits removed. - R. J. Mathar, Nov 08 2022

Status

approved