Incenter - Jenna Means

Incenter - Jenna Means
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2017-01-19 04:01
① This example demonstrates the construction of the incenter of a triangle and its associated angle bisectors, perpendicular segments, and angle labels in GeoGebra. ② Core mathematical concepts include the definition of the incenter as the intersection of internal angle bisectors, properties of angle bisectors, the inradius (distance from incenter to sides), and angle measurement. ③ Construction details: the Polygon command creates triangle ABC; AngularBisector constructs the three internal angle bisectors; Intersect finds their common point D (the incenter); Angle labels angles α, β, etc.; Segment connects vertices to the incenter; OrthogonalLine draws perpendiculars from the incenter to sides, revealing the inradius; text objects annotate the figure. ④ Suitable for middle school to high school students learning triangle centers, angle bisector theorems, and geometric construction, as well as for classroom demonstrations by teachers.

GeoGebra 命令及参数

  1. Polygon(A, B, C) → poly1, c, a, b
  2. AngularBisector(A, C, B) → f
  3. AngularBisector(C, B, A) → g
  4. AngularBisector(B, A, C) → h
  5. Intersect(f, g) → D
  6. Angle(poly1) → α, β, γ
  7. Angle(D, A, C) → δ
  8. Angle(B, A, D) → ε
  9. Angle(D, B, A) → ζ
  10. Angle(C, B, D) → η
  11. Angle(D, C, B) → θ
  12. Angle(A, C, D) → ι
  13. Segment(D, A) → i
  14. Segment(D, C) → j
  15. Segment(D, B) → k
  16. OrthogonalLine(D, c) → l
  17. OrthogonalLine(D, b) → m
  18. OrthogonalLine(D, a) → n
  19. Intersect(l, c) → E
  20. Intersect(n, a) → F
  21. Intersect(m, b) → G
  22. Segment(D, E) → p
  23. Segment(D, F) → q
  24. Segment(D, G) → r