Vector Ratio Theorem: Dividing Vectors via Parallelogram Construction

Vector Ratio Theorem: Dividing Vectors via Parallelogram Construction
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2020-12-29 09:20
This example demonstrates the vector ratio (dividing) theorem geometrically: given two vectors with compatible directions, it constructs a parallelogram-style figure and locates points on the sides using a proportional split, so the resulting segments correspond to “division” of vectors (ratio relationships). Key concepts include vectors, parallelogram geometry as a vector representation, and the use of distances/lengths to encode proportionality. The construction uses GeoGebra commands and objects such as Vector and Point to create vector endpoints, Segment to build the sides, Distance/Length to compute required metrics, and Semicircle plus PointIn to enforce or visualize allowed regions/constraints. Conditional logic via If selects constructions based on validity, while Max helps manage extremal/feasible values. Objects like mid, m, n, AB, and M serve for intermediate points and labels, and text1–text3 with button1 support parameter display and interactive results. Suitable for advanced high school and early university students learning vectors and geometric modeling, and for classroom demonstrations linking ratios and vector operations.

GeoGebra Commands & Parameters

  1. Vector(A) → u
  2. Vector(A, B) → AB
  3. Point(u) → O
  4. Semicircle(A, M) → e1
  5. Semicircle(M, B) → h_{1}
  6. Vector(M) → j
  7. Distance(A, M) → distanceAM
  8. Distance(B, M) → distanceBM
  9. Distance(A, B) → distanceAB
  10. Segment(B, M) → i
  11. Vector(B) → v
  12. Max(Sequence[If[Mod[abs(m), i] + Mod[abs(denom), i] ≟ 0, i, -1], i, 1, Min[{abs(m), abs(denom)}]]) → GCDnd1
  13. If(sgn(m / denom) > 0, "", "-") → textSignN1
  14. Max(Sequence[If[Mod[abs(n), i] + Mod[abs(denom), i] ≟ 0, i, -1], i, 1, Min[{abs(n), abs(denom)}]]) → GCDnd2
  15. If(sgn(n / denom) > 0, "", "-") → textSignN2
  16. Length(h_{1}) → b
  17. PointIn(h_{1}) → Pointh
  18. Length(e1) → d
  19. PointIn(e1) → Pointe1

AI Drawing Prompt Reference

Draw a geometric construction illustrating the vector ratio (division) theorem. Start with two given points to define two vectors and their directions. Construct two semicircles on segments tied to an intermediate point, then mark intersection/point-in regions on each semicircle to obtain the corresponding split points. Build the key sides of the parallelogram-style figure by connecting the relevant points, and place the interior point so that distances from it to each endpoint encode the required proportional division. Compute and label the lengths from the interior point to both endpoints and the length between the original endpoints, and draw the vector from the origin point to the interior point. Finally, add text labels indicating the sign of the ratio based on the chosen parameters. Follow the order: define vectors → semicircle arcs and regions → locate split points → draw segments/vectors → measure and annotate distances and signs.
The prompt above was compiled from the original drawing commands and is for reference only.