相似三角形构造
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这个范例演示了如何构造相似三角形。核心数学概念包括相似三角形的性质。使用了Segment, PointIn, If, Union等GeoGebra命令。适合初中及以上学生学习相似三角形的几何作图。
GeoGebra 命令及参数
Segment(A, B) → aSegment(B, C) → bSegment(C, A) → cPointIn(Polygon[(0.5, 0), (24, 0), (24, 13), (0.5, 13)]) → A'PointIn(Polygon[(0.5, 0), (24, 0), (24, 13), (0.5, 12)]) → C'PointIn(Polygon[(0.5, 0), (24, 0), (24, 13), (0.5, 12)]) → B'Segment(A', B') → dSegment(B', C') → eSegment(C', A') → fIf(Distance[A, B] / Distance[A', B'] ≟ Distance[B, C] / Distance[B', C'] ∧ Distance[A, B] / Distance[A', B'] ≟ Distance[A, C] / Distance[A', C'] ∨ Distance[A, B] / Distance[A', B'] ≟ Distance[B, C] / Distance[A', C'] ∧ Distance[A, B] / Distance[A', B'] ≟ Distance[A, C] / Distance[B', C'] ∨ Distance[A, B] / Distance[A', C'] ≟ Distance[B, C] / Distance[C', B'] ∧ Distance[A, B] / Distance[A', C'] ≟ Distance[A, C] / Distance[A', B'] ∨ Distance[A, B] / Distance[A', C'] ≟ Distance[B, C] / Distance[B', A'] ∧ Distance[A, B] / Distance[A', C'] ≟ Distance[A, C] / Distance[B', C'] ∨ Distance[A, B] / Distance[B', C'] ≟ Distance[B, C] / Distance[B', A'] ∧ Distance[A, B] / Distance[B', C'] ≟ Distance[A, C] / Distance[A', C'] ∨ Distance[A, B] / Distance[B', C'] ≟ Distance[B, C] / Distance[A', C'] ∧ Distance[A, B] / Distance[B', C'] ≟ Distance[A, C] / Distance[A', B'], true, false) → similarUnion(Sequence[Segment[(0, i), (25, i)], i, 0, 12], Sequence[Segment[(k, 0), (k, 12)], k, 0, 25]) → gridIf(similar ∧ Polygon[A, B, C] ≟ Polygon[A', B', C'], true, false) → congruent