Intersecting a Cone and a Sphere: Constructing the Locus Curve

Intersecting a Cone and a Sphere: Constructing the Locus Curve
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2025-07-19 03:17
This example constructs a 3D cone and a sphere, then computes their intersection positions to visualize the resulting space curve (intersection line/curve) and its global locus. It highlights core solid-geometry ideas: cone/sphere modeling, orthogonal slicing by planes, geometric intersection (finding intersection points/paths), and locus-based reasoning to represent the set of points satisfying the intersection constraints. In GeoGebra, the build relies on commands such as Intersect (intersection), Circle (circles), Point (points), Cone (cone), Sphere (sphere), OrthogonalPlane (orthogonal plane), IntersectPath (intersection of paths), and Locus (locus/trajectory). These objects—Cone, Sphere, and OrthogonalPlane—provide the geometric framework; intersections are computed with Intersect/IntersectPath and collected to generate the locus curve. Suitable for advanced secondary school geometry, geometry construction lessons, and pre-university/early college instruction on space geometry and visualization.

GeoGebra Commands & Parameters

  1. Intersect(xAxis, yAxis) → A
  2. Circle(A, 1) → c
  3. Point(zAxis) → B
  4. Cone(A, B, 1) → a, d, b
  5. Sphere(C, .5) → e
  6. Point(zAxis) → D
  7. OrthogonalPlane(D, zAxis) → p
  8. IntersectPath(p, a) → f
  9. IntersectPath(p, e) → g
  10. Intersect(f, g) → E, F, ,
  11. Locus(E, D) → lieu1
  12. Locus(F, D) → lieu2

AI Drawing Prompt Reference

Draw a 3D figure containing a cone and a sphere. The cone is defined by two points, and the sphere by a center point. Create a vertical plane intersecting the cone, and compute the intersection paths of the cone and sphere. Then, intersect these paths with the plane to obtain two points. Finally, draw trajectory lines from these points to the plane to represent the set of points satisfying the intersection constraints.
The prompt above was compiled from the original drawing commands and is for reference only.