Surface-to-Movable Plane Intersection Demo

Surface-to-Movable Plane Intersection Demo
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2016-04-28 20:12
This example demonstrates the dynamic intersection of a surface with a movable plane, involving core math concepts like 3D vectors, function graphs (logarithmic), polygon construction, and geometric transformations. Key GeoGebra commands and objects used include Function, If, Polygon, PointIn, Segment, Textfield, Point, Sum, Length, Sequence, RemoveUndefined, Zip, Append, PolyLine, ImplicitCurve, IntersectPath, suitable for high school students and math enthusiasts exploring spatial geometry and function interactions.

GeoGebra Commands & Parameters

  1. Function(f(a, b), a, x_{min} - 0.2, x_{max} + 0.2, b, y_{min} - 0.2, y_{max} + 0.2) → g
  2. If(Length[RemoveUndefined[Join[Zip[Mirror[{Roots[f0(a, x), y_{min}, y_{max}]}, y = x] + (a, 0), a, Sequence[x_{min} + ((x_{max} - x_{min}) / N_P * i), i, 0, N_P]]]]] ≟ 0, false, true) → lb1
  3. If(lb1, RemoveUndefined[Join[Zip[Mirror[{Roots[f0(a, x), y_{min}, y_{max}]}, y = x] + (a, 0), a, Sequence[x_{min} + ((x_{max} - x_{min}) / N_P * i), i, 0, N_P]]]], Sequence[(10000, 10000), k, 1, 50]) → P1xxy
  4. If(lb1, RemoveUndefined[Join[Zip[Reverse[{Roots[f0(x, a), x_{min}, x_{max}]}] + (0, a), a, Sequence[y_{min} + ((y_{max} - y_{min}) / N_P * i), i, 0, N_P]]]], Sequence[(10000, 10000), k, 1, 50]) → P2yyx
  5. Polygon((x_{min}, y_{min}), (x_{max}, y_{min}), (x_{max}, y_{max}), (x_{min}, y_{max})) → poly1, b, c, d, e
  6. PointIn(poly1) → PTest
  7. Segment(B02, B01) → a
  8. Textfield(v_1) → inputBox2
  9. Textfield(f) → inputBox3
  10. Textfield(x_{min}) → inputBox4
  11. Textfield(x_{max}) → inputBox5
  12. Textfield(y_{max}) → inputBox6
  13. Textfield(z_{max}) → inputBox7
  14. Textfield(y_{min}) → inputBox8
  15. Textfield(z_{min}) → inputBox9
  16. Point(a, 1 - zzii_B) → A
  17. Textfield(N_P) → inputBox10
  18. Sum(Sequence[If[f(x(PTest), y(PTest)) - f(x(Element[lr01, i]), y(Element[lr01, i])) > 0, 1, 0], i, 1, n]) → ext1
  19. Length(list1) → Lä
  20. Textfield(step) → inputBox12
  21. Textfield(zoom_{3D}) → InputBox1
  22. Sequence((x(Element[lr01, i]), y(Element[lr01, i]), f(x(Element[lr01, i]), y(Element[lr01, i]))), i, 1, n) → lr013
  23. Sequence((x(Element[lr02, i]), y(Element[lr02, i]), f(x(Element[lr02, i]), y(Element[lr02, i]))), i, 1, n) → lr023
  24. RemoveUndefined(Sequence[If[f(x(PTest), y(PTest)) - f(x(Element[lr01, i]), y(Element[lr01, i])) > 0, i, NaN], i, 1, n]) → lr04
  25. Zip(Vector[b, a], a, Sequence[Element[lr01, Element[lr04, i]], i, 1, Length[lr04]], b, Sequence[Element[lr02, Element[lr04, i]], i, 1, Length[lr04]]) → lr06
  26. Zip(Vector[b, a], a, Sequence[Element[lr013, Element[lr04, i]], i, 1, Length[lr04]], b, Sequence[Element[lr023, Element[lr04, i]], i, 1, Length[lr04]]) → lr063
  27. Zip(Vector[a, b], a, Sequence[Element[lr01, Element[lr05, i]], i, 1, Length[lr05]], b, Sequence[Element[lr02, Element[lr05, i]], i, 1, Length[lr05]]) → lr07
  28. Zip(Vector[a, b], a, Sequence[Element[lr013, Element[lr05, i]], i, 1, Length[lr05]], b, Sequence[Element[lr023, Element[lr05, i]], i, 1, Length[lr05]]) → lr073
  29. RemoveUndefined(Sequence[If[f(x(PTest), y(PTest)) - f(x(Element[lr01, i]), y(Element[lr01, i])) > 0, i, (-i)], i, 1, n]) → lr04c
  30. Append(lr04c, Element[lr04c, 1]) → lr04cc
  31. Sum(Sequence[If[(Element[lr04cc, i] * Element[lr04cc, i + 1]) < 0, 1, 0], i, 1, n + 1]) → lr04ccc
  32. If(ext1 ≟ n, "Max", If[ext1 ≟ 0, "Min", If[(lr04ccc > 2) ∧ (lr04ccc ≤ 4), "saddle ? ", "?"]]) → TT1
  33. PolyLine({(0, 0.5019607843), (0.1, 0.4980392157), (0.2, 0), (0.3, 0), (0.4, 0.2), (0.5, 0.2), (0.7, 1), (1, 1)}) → Ro
  34. PolyLine({(0, 0), (0.2, 0), (0.3, 0.6), (0.4, 1), (0.7, 1), (0.9, 0.2), (1, 0)}) → Gr
  35. PolyLine({(0, 0.5019607843), (0.1, 1), (0.3, 1), (0.4, 0.8), (0.5, 0), (0.6, 0), (0.7, 0.4), (0.8, 0.2), (0.9, 0.4), (1, 0)}) → Bl
  36. Point(Pxy) → D
  37. Textfield(z0) → InputBox2
  38. ImplicitCurve(g(x, y) - z0) → p
  39. IntersectPath(o, g(x, y)) → s