平行四边形面积演示 by Mark Dabbs
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①本范例演示平行四边形面积的计算方法,通过可视化方式展示底乘以高。②涉及核心数学概念包括平行四边形、面积公式、相似三角形、解析几何。③作图要点:使用 GeoGebra 命令如 Point, OrthogonalLine, Segment, Line, Intersect, Polygon, Dilate, Circle;对象包括 Translate, g, A, a, C, B_1, b, c, d, D_1, e, f, h, i, j, B, D, k, E, l, m, n, F, p, poly1, a_1, e_1, f_1, d_1, poly2, e_2, c_1, b_1, f_2, q, r, s, C', t, g_1。④适合初中及以上学生学习平行四边形面积公式及几何作图。
GeoGebra 命令及参数
Point(g) → AOrthogonalLine(A, g) → aPoint(g) → CSegment(C, B_1) → bLine(A, b) → cLine(B_1, g) → dIntersect(c, d) → D_1Segment(D_1, B_1) → eSegment(A, D_1) → fOrthogonalLine(C, g) → hOrthogonalLine(D_1, g) → iOrthogonalLine(B_1, g) → jIntersect(g, i) → BIntersect(g, j) → DSegment(If[x(B) ≥ x(A), B, A], If[x(B) ≥ x(A), C, D]) → kPoint(k) → ESegment(A, B) → lSegment(C, D) → mOrthogonalLine(E, e) → nIntersect(n, e) → FSegment(F, E) → pPolygon(A, E, F, D_1) → poly1, a_1, e_1, f_1, d_1Polygon(E, C, B_1, F) → poly2, e_2, c_1, b_1, f_2Segment(B_1, F) → qSegment(F, D_1) → rSegment(A, C) → sDilate(C, Translate, A) → C'Line(C', b) → tLine(B_1, s) → g_1Intersect(t, g_1) → GCircle(G, Segment[D_1, F]) → h_1Circle(C', Segment[A, E]) → k_1Line(A, C) → i_1Intersect(k_1, i_1) → H, IIntersect(h_1, g_1) → J, KSegment(B_1, K) → j_1Segment(K, I) → l_1Segment(I, C') → m_1Segment(G, C') → n_1Polygon(C', G, K, I) → poly3, c', g_2, k_2, i_2Segment(E, C) → p_1Segment(G, F) → q_1Segment(F, E) → r_1Segment(I, K) → s_1