Cross Sections of Cone, Sphere, and Cylinder

Cross Sections of Cone, Sphere, and Cylinder
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2018-02-10 17:30
①This example dynamically demonstrates the shapes and variations of cross sections obtained by cutting a cone, a sphere, and a cylinder with a plane, vividly illustrating the core phenomenon of cross-section problems in solid geometry. ②Core mathematical concepts involved include cross sections of solids, conic sections (circle, ellipse, parabola, hyperbola), great and small circles of a sphere, circular or elliptical sections of a cylinder, and the special role of equilateral triangles in certain sections. ③Construction highlights: Based on the construction summary, GeoGebra commands such as Point, Circle, Distance, Segment, and Intersect are used, creating objects A, f, D, B, E, c, e, d, r₂, r₃, text1, text2, g, C, F, h, i, and text3. The section plane is dynamically adjusted via control points and auxiliary lines, with text objects displaying relevant measurements or explanations. ④This is suitable for high school solid geometry teaching, introductory analytic geometry in university, and math enthusiasts exploring 3D section properties. It can be used for classroom demonstrations or self-directed exploration to enhance spatial visualization skills.

GeoGebra Commands & Parameters

  1. Point(f) → B
  2. Circle(A, B) → c
  3. Circle(E, 3) → e
  4. Circle(D, sqrt(9 - Distance[A, B]^(2))) → d
  5. Distance(A, B) → r_{3}
  6. Segment(A, B) → g
  7. Intersect(d, xAxis, 2) → C
  8. Intersect(e, xAxis, 2) → F
  9. Segment(D, C) → h
  10. Segment(E, F) → i