分数乘法演示 by Robert Fant
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①本范例通过动态演示两个分数的乘法过程,直观展示分数乘法的几何意义;②涉及核心数学概念包括分数乘法规则、几何图形(如平行四边形)的面积关系、概率与分布的基本思想;③作图要点:运用了Point, Polygon, Textfield, IndexOf, Take, Sequence, RemoveUndefined, Intersection, GCD等GeoGebra命令和对象,如mover, f2Point, f1Point, f1, f1poly等,构建分数乘法的可视化模型;④适合初中及以上数学学习者,用于理解分数乘法的本质和几何应用。
GeoGebra 命令及参数
Point({1 - mover, 0}) → f2PointPoint({-1 + mover, 0}) → f1PointPolygon(f1Point, f1Point + (f1, 0), f1Point + (f1, 1), f1Point + (0, 1)) → f1poly, f1point, n, p, qPolygon(f2Point, E, G, H) → poly3, f2point, e, g_1, h_1Textfield(f1Text) → InputBox1Textfield(f2Text) → InputBox2IndexOf(47, TextToUnicode[f1Text]) → slash1IndexOf(47, TextToUnicode[f2Text]) → slash2Take(f1Text, slash1 + 1) → D1TextPolygon(f1Point, f1Point + (1, 0), 4) → poly1, f, g, h, i, A, BPolygon(f2Point, f2Point + (1, 0), 4) → poly2, j, k, l, m, C, DTake(f2Text, slash2 + 1) → D2TextSequence(Segment[f1Point + (i / D1, 0), f1Point + (i / D1, 1)], i, 1, D1 - 1) → f1BarsSequence(Segment[f2Point + (0, i / D2), f2Point + (1, i / D2)], i, 1, D2 - 1) → f2BarsPolygon(f2Point, f2Point + (0, f2), f2Point + (1, f2), f2Point + (1, 0)) → f2poly, r, s, t, aRemoveUndefined(Sequence[If[pN / i ≟ floor(pN / i), i], i, 1, pN]) → NfactorsRemoveUndefined(Sequence[If[pD / i ≟ floor(pD / i), i], i, 1, pD]) → DfactorsIntersection(Nfactors, Dfactors) → factorsGCD(N3, D3) → GCD