卡瓦列里原理演示:棱柱体积相等性
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① 该范例演示卡瓦列里原理,通过两个高度相同、横截面积相等的棱柱展示体积相等的现象。② 涉及核心数学概念:卡瓦列里原理、立体几何体积计算、横截面积比较、棱柱与多面体的性质。③ 作图要点:使用 Polygon 创建底面多边形,Prism 生成棱柱,CurveCartesian 与 Surface 绘制截面曲线与曲面,Point、OrthogonalPlane、Intersect、PointIn 等命令构建顶点、正交平面、交线与内部点,形成完整的三维几何模型。④ 适合高中立体几何教学、大学微积分体积积分引入,也可作为几何作图与动画演示的素材。
GeoGebra 命令及参数
Polygon((1, 0, -2), (2, -3, -2), (3, 2, -2)) → poly1, a, b, cPrism(poly1, 6) → d, A, edge3, edgeAB, edgeBC, edgeAC, B, C, face1, face3, face2, faceABC, edge1, edge2Polygon((-4, 0, -2), (-3, -3, -2), (-2, 2, -2)) → poly2, e, f, gCurveCartesian(sin((π / 3 * (t + 2))) - 4, 0, t, t, -2, 4) → iCurveCartesian(sin((π / 3 * (t + 2))) - 3, -3, t, t, -2, 4) → jPolygon((-4, 0, 4), (-3, -3, 4), (-2, 2, 4)) → poly3, h, l, mCurveCartesian(sin((π / 3 * (t + 2))) - 2, 2, t, t, -2, 4) → kSurface((u * (sin((π / 3 * (t + 2))) - 4)) + ((1 - u) * (sin((π / 3 * (t + 2))) - 3)), (u * 0) + ((1 - u) * (-3)), t, t, -2, 4, u, 0, 1) → nSurface((u * (sin((π / 3 * (t + 2))) - 4)) + ((1 - u) * (sin((π / 3 * (t + 2))) - 2)), (u * 0) + ((1 - u) * 2), t, t, -2, 4, u, 0, 1) → oSurface((u * (sin((π / 3 * (t + 2))) - 2)) + ((1 - u) * (sin((π / 3 * (t + 2))) - 3)), (u * 2) + ((1 - u) * (-3)), t, t, -2, 4, u, 0, 1) → pCurveCartesian(-6, 0, t, t, -10, 10) → qPoint(q) → EOrthogonalPlane(E, zAxis) → rIntersect(edge2, r) → FIntersect(edge3, r) → GIntersect(edge1, r) → HPolygon(H, G, F) → poly4, f_1, h_1, g_1CurveCartesian((u * (sin((π / 3 * (z(E) + 2))) - 4)) + ((1 - u) * (sin((π / 3 * (z(E) + 2))) - 3)), (u * 0) + ((1 - u) * (-3)), z(E), u, 0, 1) → sPolygon(I, J, K) → poly5, k_1, i_1, j_1PointIn(poly4) → Pointpoly4PointIn(poly5) → Pointpoly5