三角形中线与重心的探索
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① 本范例演示三角形的三条中线及其交点——重心的位置关系;② 涉及中线定理、重心性质、向量分割比例等核心数学概念;③ 作图使用 GeoGebra 命令 Midpoint(取中点)、Segment(画线段)、Intersect(求交点)、Dilate(缩放)、Rotate(旋转)、Polygon(构建多边形),并创建顶点 A、B、C 及中点 D、E、F、重心 G 等对象;④ 适合初中几何教学、高中解析几何复习以及几何作图训练。
GeoGebra 命令及参数
Midpoint(A, B) → DMidpoint(B, C) → EMidpoint(C, A) → FSegment(A, B) → aSegment(B, C) → bSegment(C, A) → cSegment(C, D) → dSegment(A, E) → eSegment(B, F) → fIntersect(d, e) → GDilate(A, If[0 < g ≤ 1, 1 - g, 0], D) → A'Segment(A, A') → hRotate(A, If[1 < g ≤ 2, ((g - 1) * π), 3.141592653589793], D) → A'_1Rotate(A', If[1 < g ≤ 2, ((g - 1) * π), 3.141592653589793], D) → A''Segment(A'_1, A'') → h'Dilate(B, If[2 < g ≤ 3, 3 - g, 0], E) → B'Segment(B, B') → iRotate(B, If[3 < g ≤ 4, ((g - 3) * π), 3.141592653589793], E) → B'_1Rotate(B', If[3 < g ≤ 4, ((g - 3) * π), 3.141592653589793], E) → B''Segment(B'_1, B'') → i'Dilate(C, If[4 < g ≤ 5, 5 - g, 0], F) → C'Segment(C, C') → jRotate(C, If[5 < g ≤ 6, ((g - 5) * π), 3.141592653589793], F) → C'_1Rotate(C', If[5 < g ≤ 6, ((g - 5) * π), 3.141592653589793], F) → C''Segment(C'_1, C'') → j'Midpoint(G, C) → HMidpoint(G, B) → IMidpoint(A, G) → JDilate(C, If[6 < g ≤ 7, 7 - g, 0], H) → C'_2Segment(C, C'_2) → kDilate(H, If[7 < g ≤ 8, 8 - g, 0], G) → H'Segment(H, H') → lDilate(G, If[8 < g ≤ 9, 9 - g, 0], D) → G'Segment(G, G') → mDilate(A, If[9 < g ≤ 10, 10 - g, 0], J) → A'_2Segment(A, A'_2) → nDilate(J, If[10 < g ≤ 11, 11 - g, 0], G) → J'Segment(J, J') → pDilate(G, If[11 < g ≤ 12, 12 - g, 0], E) → G'_1Segment(G, G'_1) → qPolygon(A, B, C) → poly1, c_1, a_1, b_1Dilate(F, If[12 < g ≤ 13, 13 - g, 0], G) → F'Segment(F, F') → rRotate(F, If[14 < g ≤ 15, ((g - 14) * π), 3.141592653589793], G) → F'_1Rotate(F', If[14 < g ≤ 15, ((g - 14) * π), 3.141592653589793], G) → F''Segment(F'_1, F'') → r'Rotate(F'_1, If[15 < g ≤ 16, ((g - 15) * π), 3.141592653589793], I) → KRotate(F'', If[15 < g ≤ 16, ((g - 15) * π), 3.141592653589793], I) → F'''Segment(K, F''') → r''Rotate(G, If[16 < g ≤ 17, ((g - 16) * π), 3.141592653589793], G) → G'_2Rotate(G'_1, If[16 < g ≤ 17, ((g - 16) * π), 3.141592653589793], G) → LSegment(G'_2, L) → q'Rotate(G'_2, If[17 < g ≤ 18, ((g - 17) * π), 3.141592653589793], J) → MRotate(L, If[17 < g ≤ 18, ((g - 17) * π), 3.141592653589793], J) → L'Segment(M, L') → q''Rotate(G, If[18 < g ≤ 19, ((g - 18) * π), 3.141592653589793], G) → G'_3Rotate(G', If[18 < g ≤ 19, ((g - 18) * π), 3.141592653589793], G) → G''Segment(G'_3, G'') → m'Rotate(G'_3, If[19 < g ≤ 20, ((g - 19) * π), 3.141592653589793], H) → NRotate(G'', If[19 < g ≤ 20, ((g - 19) * π), 3.141592653589793], H) → G'''Segment(N, G''') → m''
AI 绘图提示语参考
画一个任意三角形,标出三边的中点,连接各顶点到对边中点形成三条中线,三条中线交于重心。同时标出重心到三个顶点的线段中点,展示重心将每条中线按 2:1 分割的性质。
以上提示语为根据原始绘图命令整理而来,仅供参考。