旋转体生成圆锥与圆柱 by Kevin Westrich
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①本范例演示通过旋转二维图形生成圆锥和圆柱的三维立体图形;②涉及的核心数学概念包括旋转体、三维几何、解析几何;③作图要点——从下方『构造摘要』提炼用到了Vector(向量)、Polygon(多边形)、Sequence(数列)、CurveCartesian(笛卡尔曲线)等GeoGebra命令/对象;④适合高中及以上学生学习和理解旋转体几何与三维建模。
GeoGebra 命令及参数
Vector(((1.1 * d) * W_x)) → uVector(((1.1 * d) * W_y)) → vVector(((1.1 * d) * W_z)) → wPolygon(((1.1 * d) * (W_x + W_y)), ((1.1 * d) * ((-W_x) + W_y)), ((1.1 * d) * ((-W_x) - W_y)), ((1.1 * d) * (W_x - W_y))) → poly1, g, i, j, lSequence(((r * cos((0.125 * i))) * W_x) + ((r * sin((0.125 * i))) * W_y), i, 0, p) → list1Sequence(((r * cos((0.125 * i))) * W_x) + ((r * sin((0.125 * i))) * W_y) + (k * W_z), i, 0, p) → list3CurveCartesian(x(((r * cos((0.125 * i))) * W_x) + ((r * sin((0.125 * i))) * W_y)), y(((r * cos((0.125 * i))) * W_x) + ((r * sin((0.125 * i))) * W_y)), i, 0, p) → e_1CurveCartesian(x(((r * cos((0.125 * t))) * W_x) + ((r * sin((0.125 * t))) * W_y) + (k * W_z)), y(((r * cos((0.125 * t))) * W_x) + ((r * sin((0.125 * t))) * W_y) + (k * W_z)), t, 0, p) → e_2Sequence(Segment[A, Element[list1, i]], i, 1, p + 1) → list2Sequence(Segment[Element[list1, i], Element[list3, i]], i, 1, p + 1) → list4Sequence(Segment[(0, 0) + (k * W_z), Element[list3, i]], i, 1, p + 1) → list5