任意边构建等边三角形动态演示
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①本范例动态演示在任意图形边构建等边三角形的过程与性质;②涉及核心数学概念包括等边三角形构造、旋转、向量、参数方程、几何变换等;③作图要点运用了Segment、Rotate、Angle、Point、Polygon、Midpoint、Dilate、Vector、Translate、Line等GeoGebra命令与对象;④适合高中及以上数学教学与几何作图探索。
GeoGebra 命令及参数
Segment(A, B) → fRotate(B, (a * π / 180), A) → B'Angle(B, A, B') → αRay(A, B') → gPoint(g) → CSegment(B, C) → hSegment(A, C) → iPolygon(A, B, C) → poly1, c, a_1, bPolygon(C, B, 3) → poly2, j, k, l, DPolygon(A, C, 3) → poly3, m, n, p, ERotate(A, If[0 < d ≤ 1, (d * π / 3), π / 3], A) → A'Rotate(C, If[0 < d ≤ 1, (d * π / 3), π / 3], A) → C'Segment(A', C') → i'Rotate(B, If[0 < d ≤ 1, (d * π / 3), π / 3], C) → B'_1Rotate(C, If[0 < d ≤ 1, (d * π / 3), π / 3], C) → C'_1Segment(B'_1, C'_1) → h'Rotate(B'_1, If[1 < d ≤ 2, ((d - 1) * π / 3), π / 3], D) → IRotate(C'_1, If[1 < d ≤ 2, ((d - 1) * π / 3), π / 3], D) → JSegment(I, J) → h''Rotate(A', If[1 < d ≤ 2, ((d - 1) * π / 3), π / 3], E) → A''Rotate(C', If[1 < d ≤ 2, ((d - 1) * π / 3), π / 3], E) → C''Segment(A'', C'') → i''Midpoint(E, D) → LDilate(D, If[4 < d ≤ 5, 5 - d, 0], L) → D'Dilate(L, If[5 < d ≤ 6, 6 - d, 0], E) → L'Rotate(D, If[6 < d ≤ 7, ((-(d - 6)) * π), (-π)], L) → D'_1Rotate(D', If[6 < d ≤ 7, ((-(d - 6)) * π), (-π)], L) → D''Dilate(A, If[3 < d ≤ 4, 4 - d, 0], D) → A'_1Dilate(D, If[5 < d ≤ 6, 6 - d, 0], B) → D'_2Vector(D, D'_2) → uTranslate(A, u) → A'_2Translate(A'_1, u) → FSegment(A'_2, F) → q'Line(E, B) → sSegment(A, B) → qRotate(A, If[2 < d ≤ 3, ((d - 2) * π / 3), π / 3], A) → A'_3Rotate(B, If[2 < d ≤ 3, ((d - 2) * π / 3), π / 3], A) → B'_2Segment(A'_3, B'_2) → q'_1Rotate(A'_3, If[3 < d ≤ 4, ((d - 3) * π / 3), π / 3], B'_2) → GRotate(B'_2, If[3 < d ≤ 4, ((d - 3) * π / 3), π / 3], B'_2) → HSegment(G, H) → rPolygon(A, B'_2, B) → t1, b_1, a_2, b'_2Dilate(C, If[5 < d ≤ 6, 6 - d, 0], E) → C'_2Vector(C, C'_2) → vTranslate(B'_1, v) → KTranslate(C'_1, v) → MSegment(K, M) → h''_1Dilate(C, If[6 < d ≤ 7, 7 - d, 0], D) → C'_3Vector(C, C'_3) → wTranslate(A'', w) → A'''Translate(C'', w) → C'''Segment(A''', C''') → i'''Polygon(E, C, D, B'_2) → q1, e, c_1, d_1, b'_1