Dynamic Points and Limits in a Parallelogram (Q7)

Dynamic Points and Limits in a Parallelogram (Q7)
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2019-09-17 12:51
①This example demonstrates the construction of a sequence of dynamic points within a parallelogram framework, observing their limiting positions and angle variations. ②Core mathematical concepts include parallelogram properties, vector translation and duplication, dynamic coordinates, sequences, limits, and angle measurement. ③Construction highlights: using GeoGebra commands such as Point, Vector, Sequence, DynamicCoordinates, Segment, Intersect, Polygon, If, and Angle, it creates base points A, B, C1, generates point sequences UPoints and VPoints via vectors u and v, duplicates vectors uCopy and vCopy to form parallel lines, finds intersections C and C', and constructs polygons with angle labels, possibly involving numerical limit approximation. ④Suitable for high school or early college students to intuitively grasp vector geometry, dynamic construction, and limit concepts, and can serve as material for mathematical experiments or inquiry-based learning.

GeoGebra Commands & Parameters

  1. Point(Sequence[A + (i, 0), i, 1, 20, 1]) → B
  2. Vector(A, C1) → u
  3. Sequence(A + (i * UnitVector[Segment[A, C1]]), i, 1, 20, 1) → UPoints
  4. DynamicCoordinates(C1, x(ClosestPoint[UPoints, C1]), y(ClosestPoint[UPoints, C1])) → C
  5. Vector(B, C2) → v
  6. Sequence((x(B) + (Length[v] * cos(t°)), y(B) + (Length[v] * sin(t°))), t, 0, 355, 5) → VPoints
  7. DynamicCoordinates(C2, x(ClosestPoint[VPoints, C2]), y(ClosestPoint[VPoints, C2])) → C'
  8. Segment(A, C) → f
  9. Intersect(Circle[A, f], Line[B, C']) → G, G'
  10. Segment(A, B) → g
  11. Segment(C', B) → h
  12. Polygon(A, B, G) → t1, g_1, a, b
  13. Polygon(A, B, G') → t2, i, j, k
  14. If(C ≟ G ∧ C' ≟ G, true, false) → closed1
  15. If(C ≟ G' ∧ C' ≟ G', true, false) → closed2
  16. Angle(C', B, A) → α
  17. Intersect(Circle[D, 7], Ray[E, Rotate[D, (-(90°)), E]]) → F,
  18. Polygon(D, E, F) → t3, f_1, d_1, e
  19. Angle(F, E, D) → β