Vertical Cross Sections of a Triangular Pyramid

Vertical Cross Sections of a Triangular Pyramid
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2020-02-28 07:39
This GeoGebra example dynamically demonstrates how the cross-section of a triangular pyramid (tetrahedron) changes when cut by a vertical plane. The core mathematical concepts involve solid geometry, spatial plane intersections, and the properties of polyhedral sections. Construction highlights: using Point and Pyramid commands to define vertices A, B, C, D and faces/edges; employing Plane and IntersectPath to generate intersection lines between the cutting plane and pyramid faces, forming the section polygon; using PointIn and sliders to move the cutting plane for dynamic observation. Suitable for high school solid geometry lessons or introductory university spatial analytic geometry, this tool helps students visualize how section shapes evolve with plane position and enhances spatial reasoning skills.

GeoGebra Commands & Parameters

  1. Point(xAxis) → C
  2. Point(zAxis) → D
  3. Pyramid(A, B, C, D) → a, faceABC, edgeCD, faceABD_1, faceBCD, faceACD, edgeAB, edgeBC, edgeAC, edgeAD, edgeBD
  4. Pyramid(faceABD_1, A) → b, faceAAB, faceABD, faceAAD, edgeAA, edgeAB, edgeAD
  5. Intersect(edgeAC, yAxis) → E
  6. Intersect(edgeBC, yAxis) → F
  7. Point(edgeAC) → G
  8. Point(edgeBC) → H
  9. Point(edgeCD) → I
  10. Point(edgeBD) → L
  11. Point(edgeAD) → M
  12. Point(edgeBC) → N
  13. Plane(L, M, N) → r
  14. IntersectPath(r, faceABD) → g
  15. Intersect(r, faceABD) → O, P
  16. IntersectPath(r, faceACD) → f
  17. Intersect(r, faceACD) → J, K
  18. IntersectPath(r, faceBCD) → h
  19. Intersect(r, faceBCD) → Q, R
  20. IntersectPath(r, a) → poly1, S, T, U, V, i, j, k, l
  21. Plane(G, H, I) → p
  22. IntersectPath(p, faceACD) → m
  23. Intersect(p, faceACD) → W, Z
  24. IntersectPath(p, a) → poly2, A_1, B_1, C_1, n, q, s
  25. IntersectPath(xOyPlane, faceBCD) → t
  26. Intersect(xOyPlane, faceBCD) → D_1, E_1
  27. Plane(E, D, F) → p_1
  28. IntersectPath(p_1, a) → poly3, F_1, G_1, H_1, c, d, e
  29. Point(edgeCD) → I_1
  30. Point(t) → J_1
  31. Point(edgeAC) → K_1
  32. Plane(I_1, J_1, K_1) → q_1
  33. IntersectPath(q_1, faceBCD) → f_1
  34. Intersect(q_1, faceBCD) → L_1, M_1
  35. IntersectPath(q_1, a) → poly4, N_1, O_1, P_1, g_1, h_1, i_1
  36. Point(t) → Q_1
  37. Point(edgeAC) → R_1
  38. Plane(L, M, N) → r_1
  39. Point(yAxis) → S_1
  40. Plane(F, D, S_1) → p_2
  41. IntersectPath(p_2, a) → poly5, T_1, U_1, V_1, j_1, k_1, l_1
  42. PointIn(faceABD) → W_1
  43. Plane(Q_1, R_1, W_1) → q_2
  44. IntersectPath(q_2, b) → poly6, Z_1, A_2, m_1, n_1
  45. IntersectPath(q_2, a) → poly7, B_2, C_2, D_2, E_2, s_1, t_1, a_1, b_1

AI Drawing Prompt Reference

Draw a triangular pyramid and a vertical plane cutting through it to visualize the cross-section. Use a slider to dynamically change the plane's position and observe how the cross-section polygon changes. Start by constructing the pyramid with its four vertices and edges, then draw the intersection lines between the plane and the pyramid's faces to form the cross-section, and finally use the slider to animate the plane's movement and the resulting shape changes.
The prompt above was compiled from the original drawing commands and is for reference only.