Centroid of a Triangle: Geometric Construction and Properties by dcp

Centroid of a Triangle: Geometric Construction and Properties by dcp
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2017-02-15 00:38
This GeoGebra example demonstrates the construction of the centroid (barycenter) of a triangle, which is the intersection point of its three medians. The core mathematical concept is the centroid, a point that divides each median into a 2:1 ratio, with the longer segment adjacent to the vertex. The construction uses the Polygon command to create triangle ABC, the Midpoint command to find the midpoints D, E, F of the sides, and the Line or Segment commands to draw the medians AD, BE, and CF. The Intersect command is then used to locate the common point P of these medians, which is the centroid. Additional segments from the centroid to vertices and midpoints are drawn, and text labels display the length ratios, visually confirming the 2:1 division property. This example is suitable for middle school and above students learning about triangle centers, and is also useful for teachers demonstrating geometric constructions and dynamic exploration of centroid properties.

GeoGebra Commands & Parameters

  1. Line(A, B) → a
  2. Line(B, C) → b
  3. Line(A, C) → c
  4. OrthogonalLine(A, b) → d
  5. OrthogonalLine(B, c) → e
  6. OrthogonalLine(C, a) → f
  7. Polygon(A, B, C) → triangle, c_1, a_1, b_1
  8. Midpoint(A, B) → F
  9. Midpoint(B, C) → D
  10. Midpoint(A, C) → E
  11. Segment(A, D) → AD
  12. Segment(B, E) → BE
  13. Segment(C, F) → CF
  14. Intersect(AD, BE) → P
  15. Segment(A, E) → AE
  16. Segment(C, E) → CE
  17. Segment(B, D) → BD
  18. Segment(C, D) → CD
  19. Segment(A, F) → AF
  20. Segment(B, F) → BF
  21. Midpoint(C, P) → midCP
  22. Midpoint(F, P) → midPF
  23. Midpoint(A, P) → midAP
  24. Midpoint(D, P) → midPD
  25. Midpoint(B, P) → midBP
  26. Midpoint(E, P) → midPE