分数乘法演示 by Anthony Dove
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①本范例演示了两个真分数相乘的几何意义与计算过程;②涉及核心数学概念包括分数乘法、面积计算、几何表示;③作图要点:使用 GeoGebra 命令如 FromBase, Intersect, Point, Polygon, Segment, Textfield, Sequence, If 构建图形,展示分数乘积的直观理解;④适合初中数学教学,用于帮助学生理解分数乘法的本质。
GeoGebra 命令及参数
FromBase(td_2, 10) → d_2Intersect(xAxis, yAxis) → APoint(xAxis) → A_1Polygon(A, A_1, 4) → poly1, a_1, a_2, a_3, a_4, A_2, A_3Segment(A_3, A_2) → j_tTextfield(tn_1) → InputBox1Textfield(td_1) → InputBox2Textfield(tn_2) → InputBox3Textfield(td_2) → InputBox4Textfield(tn_3) → InputBox5Textfield(td_3) → InputBox6Point(j) → E_1Point(j) → E_2Segment(E_1, E_2) → e_1Point(j) → E_3Point(j) → E_4Segment(E_3, E_4) → e_2Point(j) → E_5Point(j) → E_6Segment(E_5, E_6) → e_3FromBase(tn_1, 10) → n_1FromBase(tn_2, 10) → n_2FromBase(tn_3, 10) → n_3FromBase(td_1, 10) → d_1FromBase(td_3, 10) → d_3Segment(A, A_3) → j_lSequence((x(A), y(A) + (i * j_l / d_1)), i, 0, d_1) → plSequence((x(A_1), y(A_1) + (i * j_l / d_1)), i, 0, d_1) → prSequence(Segment[Element[pl, i], Element[pr, i]], i, 1, d_1 + 1) → list1Segment(A_2, A_1) → j_rSequence((x(A_3) + (i * j_t / d_2), y(A_3)), i, 0, d_2) → ptSequence((x(A) + (i * j_t / d_2), y(A)), i, 0, d_2) → pbSequence(Segment[Element[pt, i], Element[pb, i]], i, 1, d_2 + 1) → list2Segment(A, A_1) → j_bIntersect(Element[list2, n_2 + 1], j_b) → P_1Intersect(Element[list2, n_2 + 1], Element[list1, n_1 + 1]) → P_2Polygon(A, Element[pl, n_1 + 1], P_2, P_1) → Poly_{Sol}, P_{Sola}, P_{Solb}, P_{Solc}, P_{Sold}Sequence((x(P_1), y(P_1) + (i * j_r / d_1)), i, 0, d_1) → list3Sequence(Segment[Element[pl, i], Element[list3, i]], i, 1, d_1 + 1) → list_{sol}Polygon(A, Element[pl, n_1 + 1], Element[pr, n_1 + 1], A_1) → Poly_{First}, P_{1d}, P_{1a}, P_{1b}, P_{1c}Polygon(A, A_3, Element[pt, n_2 + 1], P_1) → Poly_{Sec}, P_{2a}, P_{2b}, P_{2c}, P_{2d}FromBase(td_4, 10) → d_4Textfield(tn_4) → InputBox3_1Textfield(td_4) → InputBox4_1FromBase(tn_4, 10) → n_4FromBase(td_5, 10) → d_5Textfield(tn_5) → InputBox1_1Textfield(td_6) → InputBox2_1Textfield(tn_6) → InputBox3_2Textfield(td_5) → InputBox4_2FromBase(tn_5, 10) → n_5FromBase(tn_6, 10) → n_6FromBase(td_6, 10) → d_6If(c ≟ 1 ∧ d ≟ 1, d ≟ 0, d ≟ 1) → e