cerchio indu
Author: e.s.

Orientarsi con il Sole

circonferenza

meridiana

equinoziale

Muovi il punto S e vedi come varia l'ombra. 
L'ombra più corta si ha a mezzodì.

A = Intersect(xAxis, yAxis)
B = Point(yAxis)
a = Segment(A, B)
C = Point(xAxis)
c = Circle(A, C)
b = OrthogonalLine(B, a)
Est = Intersect(c, b, 2)
Ovest = Intersect(c, b, 1)
F, Mezzodì = Intersect(c, yAxis)
d = Circle(A, C)
e = CircumcircleArc(Est, Mezzodì, Ovest)
I = Point(yAxis)
J = (-34.350698551470465, -20.480913381459636)
g = Hyperbola(I, Mezzodì, J)
M = Point(e)
k = OrthogonalLine(M, a)
N = Intersect(e, k, 2)
p = CircumcircleArc(M, Mezzodì, N)
S = Point(p)
h = Line(S, B)
D = Intersect(g, h, 1)
i = Segment(A, D)
j = Segment(S, D)
E = Point(a)
l = OrthogonalLine(E, a)
K = Point(l)
K' = Mirror(K, yAxis)
L = (-28.553222807082122, -15.885353340176186)
m = Line(K, L)
n = Line(K', m)
q = Line(L, l)
O = Intersect(n, q)
poli1, k_1, k', o, l_1 = Polygon(K, K', O, L)
r = Segment(A, B)
poli2, k_2, k'_1, o_1, l_2 = Polygon(K, K', O, L)
s = Circle(A, B)
H = Point(s)
equinoziale = OrthogonalLine(H, r)
P = Intersect(s, equinoziale, 2)
a_1 = OrthogonalLine(A, r)
Q = Intersect(s, a_1, 2)
R = Intersect(s, a_1, 1)
c_1 = CircleArc(A, Q, R)
w = true
meridiana = Ray(A, I)
v = false
u = true
f = Circle(S, 2.5)