init_elements() 
z.O = point(0, 0)
z.T = point(4, 0)
C.OT = circle(z.O, z.T)
z.A = C.OT:point(0.05)
z.B = C.OT:point(0.20)
z.M = C.OT:midarc(z.A, z.B)
-- circle tangent to (OA) and (OB) through M, inside the sector
local centers = line(z.O, z.A):c_ll_p(line(z.O, z.B), z.M)
for i = 1, centers:count() do
  local c = centers:get(i)
  if point.abs(c - z.O) < point.abs(z.M - z.O) then z.W = c end
end
z.H = intersection(line(z.A, z.B), line(z.O, z.M))
L.pp = line(z.A, z.B):parallel_from(z.M)
z.D = intersection(L.pp, line(z.O, z.B))