无字证明:奇数和
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①本范例通过动态图形演示奇数和的累加构成一个正方形的现象;②涉及的核心数学概念包括数列、几何图形构造和代数证明;③作图要点:运用了Sequence(数列)、Vector(向量)、Join(连接)、Polygon(多边形)、Element(元素)、Midpoint(中点)等GeoGebra命令;④适合初中及以上学生学习数列求和、几何证明及数学可视化。
GeoGebra 命令及参数
Sequence(Sequence[(i, j), i, 0, n - 1 - j], j, 0, n - 1) → list1Sequence(Sequence[(n + 1 - j + i, j - 1), i, 0, n - 1 - j], j, 1, n - 1) → list2Vector((-1, 1)) → uJoin(Sequence[Sequence[Translate[(n + 1 - j + i, j - 1), Vector[((k * u) * (i + 1))]], i, 0, n - 1 - j], j, 1, n - 1]) → list3Sequence(Polygon[(0, n - 1), (0, n - 1 - i), 4], i, 1, n - 1) → listPolySequence(Sequence[(i, j), i, 0, n - 1 - j], j, 0, n - 1, 2) → l1Sequence(Sequence[Translate[(n + 1 - j + i, j - 1), Vector[((k * u) * (i + 1))]], i, 0, n - 1 - j], j, 1, n - 1, 2) → l3Sequence(Segment[(0, i), ((2 * n) - 2 - (2 * i), i)], i, 0, n - 2) → listSegmentSequence(Segment[(0, i), ((2 * n) - (n + 1) - i, i)], i, 0, n - 2) → l2Sequence(((2 * n) - (n + 1) - i, i), i, 0, n - 2) → l5Join(Sequence[Sequence[Translate[(n + 1 - j + i, j - 1), Vector[((k * u) * (i + 1))]], i, 0, n - 1 - j], j, 1, n - 1, 1]) → l4Vector(Element[l5, 1], Element[list3, 1]) → vSequence(Translate[Element[l5, i], Vector[((n - i) * v)]], i, 1, Length[l5]) → l6Sequence(Segment[Element[l5, i], Element[l6, i]], i, 1, Length[l5]) → l7Polygon((0, n - 1), (0, 0), 4) → poly1Sequence(Text[(2 * k) + 1, (-1.1, n - k - 1.1)], k, 0, n - 1) → l8Sequence(Text[(2 * k) + 1 + "+"], k, 0, n - 1) → l9Sequence(A + ((1.15 * i), 0), i, 0, n) → l10Sequence(Text[Element[l8, k] + " + ", Element[l10, k]], k, 1, n) → l11Element(l5, 1) → MMElement(l6, 1) → NNMidpoint(B, C) → DVector(D, B) → wVector(D, C) → a