动画275:椭圆与角度、概率统计的几何构造演示
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该范例通过GeoGebra动态演示了一个包含椭圆、圆、角、向量及概率统计元素的复杂几何构造动画。核心数学概念涉及椭圆的性质、角度旋转、向量平移与缩放、以及概率统计中的随机特征表示。作图要点包括使用Circle、Point、Line、Intersect等基础命令构建图形框架,通过CircleArc、Segment、Rotate、Angle、Ray等命令生成动态角度与弧线,利用Dilate、Vector、Translate实现几何变换,并借助Min、CircleSector等命令优化图形显示。整个构造包含大量对象(如A、B、c、C、f、D等),通过滑块或动画控制参数变化,展示几何元素间的动态关联。适合高中及以上学段的学生用于理解椭圆、角度变换与概率统计的几何可视化,也可作为教师制作交互式数学课件的参考。
GeoGebra 命令及参数
Circle(A, B) → cPoint(c) → CLine(A, C) → fIntersect(c, f, 2) → DCircleArc(A, C, D) → dCircleArc(A, D, C) → eSegment(A, C) → gCircle(D, g) → hRotate(C, (3 * π / 4), A) → C'Angle(C, A, C') → αRay(A, C') → jCircleArc(A, C, C') → kCircleArc(A, C', D) → pPoint(p) → FCircle(F, g) → qIntersect(q, f) → H, IDilate(C, If[0 < a ≤ 1, 1 - a, 0], A) → C'_1Segment(C, C'_1) → iDilate(I, If[1 < a ≤ 2, 2 - a, 0], D) → I'Segment(A, I') → lRay(H, F) → mIntersect(k, m, 1) → EDilate(D, If[2 < a ≤ 3, 3 - a, 0], H) → D'Segment(D, D') → nDilate(H, If[3 < a ≤ 4, 4 - a, 0], F) → H'Segment(H, H') → rDilate(F, If[4 < a ≤ 5, 5 - a, 0], E) → F'Segment(F, F') → sAngle(C, A, E) → βRotate(C, β / 3, A) → C'_2Angle(C, A, C'_2) → γRotate(C'_2, β / 3, A) → GAngle(C'_2, A, G) → δRay(A, G) → tRay(A, C'_2) → bRay(A, E) → f_1Angle(C, H, E) → εRotate(A, If[5 < a ≤ 6, ((a - 5) * ε), ε], D) → A'Rotate(I', If[5 < a ≤ 6, ((a - 5) * ε), ε], D) → I''Segment(A', I'') → l'Dilate(D, If[6 < a ≤ 7, 7 - a, 0], H) → D'_1Vector(D, D'_1) → uTranslate(A', u) → A''Translate(I'', u) → I'''Segment(A'', I''') → l''Segment(H, D) → g_1Min(g_1, Distance[A, C]) → oCircle(A, (0.4 * o)) → c_1Dilate(A, If[7 < a ≤ 8, 8 - a, 0], E) → A'_1Dilate(A, If[7 < a ≤ 8, 8 - a, 0], G) → A'_2Dilate(A, If[7 < a ≤ 8, 8 - a, 0], C'_2) → A'_3Segment(A, A'_1) → h_1Segment(A, A'_2) → i_1Segment(A, A'_3) → j_1Segment(A, E) → k_1Segment(A, G) → l_1Intersect(c_1, k_1, 1) → JIntersect(c_1, l_1, 1) → KCircleSector(A, K, J) → d_1Rotate(d_1, If[9 < a ≤ 10, ((-(a - 9)) * ε), (-ε)], A) → e_1Rotate(e_1, If[11 < a ≤ 12, ((-(a - 11)) * ε), (-ε)], A) → p_1Dilate(A, If[13 < a ≤ 14, 14 - a, 0], H) → A'_4Vector(A, A'_4) → vTranslate(p_1, v) → q_1