There's no need for all this dynamic stuff, you can use Solve[]
in conjunction with Manipulate[]
, and let Manipulate[]
handle the dynamic stuff.
Manipulate[
h = x /. Quiet@
Solve[2 ==
x*Cos[θ] - (p*x^2)/(6*c*d) (3 f + x) Sin[θ], x,
Reals][[1]];
Show[{Graphics[{Opacity[0.5], Red, Rectangle[{1, 0}, {2, 1}]},
PlotRange -> {{-1, 2}, {-3, 3}}, Axes -> True,
AxesOrigin -> {0, 0}],
ParametricPlot[{x*
Cos[θ] - (p*x^2)/(6*c*d) (3 f + x) Sin[θ],
x*Sin[θ] + (p*x^2)/(6*c*d) (3 f + x) Cos[θ] +
h*Sin[θ] + (p*h^2)/(6*c*d) (3 f + h) Cos[θ] +
i}, {x, 0, h}, Axes -> True]}], {ρ, 0, 1, 0.1}, {c, 0.2, 2,
0.2}, {d, 0.2, 2, 0.2}, {f, 0, 2, 0.2}, {p, 0, 2, 0.2}, {θ,
0, π, 0.1 π}, {i, -2, 2, 0.5}]