装饰多边形
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①本范例演示通过变换三角形生成装饰性多边形图案的过程;②涉及核心数学概念包括多边形变换、对称性、几何作图;③作图要点:运用了Polygon(多边形)、Intersect(交点)、Point(点)、PointIn(点在对象上)、Sequence(序列)、Mirror(镜像)、Midpoint(中点)、Rotate(旋转)、PolyLine(多段线)、Translate(平移)等GeoGebra命令与对象;④适合高中数学教学,用于理解变换与镶嵌图案的构造。
GeoGebra 命令及参数
Polygon(A, B, n) → poly1, f, q, s, t, C, D, F, G, H, I, J, g, K, S, T, h, i, j, k, l, m, pIntersect(Ray[Rotate[A, (180° - (360 * ° / n)) / 2, A], Rotate[B, (180° - (360 * ° / n)) / 2, A]], Ray[Rotate[B, ((-(180° - (360 * ° / n)))) / 2, B], Rotate[A, ((-(180° - (360 * ° / n)))) / 2, B]]) → EPoint(Polygon[A, B, E]) → LPoint(Polygon[A, B, E]) → MPoint(Polygon[A, B, E]) → NPolygon(L, M, N) → poly2, n_1, l_1, m_1PointIn(Polygon[A, B, E]) → OPointIn(Polygon[A, B, E]) → PPointIn(Polygon[A, B, E]) → QPolygon(O, P, Q) → poly3, q_1, o, p_1Sequence(Polygon[Rotate[L, ((i * 720) * ° / n), E], Rotate[M, ((i * 720) * ° / n), E], Rotate[N, ((i * 720) * ° / n), E]], i, 1, n / 2) → list1Sequence(Polygon[Rotate[O, ((i * 720) * ° / n), E], Rotate[P, ((i * 720) * ° / n), E], Rotate[Q, ((i * 720) * ° / n), E]], i, 1, n / 2) → list2Mirror(list1, Line[A, E]) → list1'Mirror(list2, Line[A, E]) → list2'Midpoint(A, B) → RRotate(L, 180°, R) → L'Rotate(M, 180°, R) → M'Rotate(N, 180°, R) → N'Rotate(O, 180°, R) → O'Rotate(P, 180°, R) → P'Rotate(Q, 180°, R) → Q'Mirror(list1', Line[C, B]) → list1''Mirror(list2', Line[C, B]) → list2''Rotate(list1, 180°, R) → list1'_1Rotate(list2, 180°, R) → list2'_1PolyLine(A, B, E, A) → rMirror(E, Line[A, B]) → E'Mirror(list1'_1, Line[E', B]) → list5Mirror(list2'_1, Line[E', B]) → list7Translate(Rotate[{list1, list1'}, (-360 * ° / n), A], A - B) → list9Translate(Rotate[{list2, list2'}, (-360 * ° / n), A], A - B) → list10Sequence(Rotate[list9, (((i * 360))° * (1 + a) / n), E], i, 1, n / (1 + a)) → list11Sequence(Rotate[list10, (((i * 360))° * (1 + a) / n), E], i, 1, n / (1 + a)) → list12Sequence(Rotate[list1'_1, (((i * (1 + a)) * 360) * ° / n), E], i, 1, n / (1 + a)) → list3Sequence(Rotate[list5, (((i * (1 + a)) * 360) * ° / n), E], i, 1, n / (1 + a)) → list6Sequence(Rotate[list2'_1, (((i * (1 + a)) * 360) * ° / n), E], i, 1, n / (1 + a)) → list4Sequence(Rotate[list7, (((i * (1 + a)) * 360) * ° / n), E], i, 1, n / (1 + a)) → list8Mirror(list2, U) → list2'_2Mirror(list2', U) → list2''_1Mirror(list1', U) → list1''_1Mirror(list1, U) → list1'_2Sequence(Rotate[{list2''_1, list2'_2}, (((i * (1 + a)) * 360) * ° / n), E], i, 1, n / (1 + a)) → list13Sequence(Rotate[{list1''_1, list1'_2}, (((i * (1 + a)) * 360) * ° / n), E], i, 1, n / (1 + a)) → list14