圆锥截面演示 by Bernat
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①本范例演示圆锥与不同几何元素(直线、平面)相交形成的各种截面图形;②涉及核心数学概念包括圆锥、截面、解析几何、向量运算;③构造过程中运用了Line(直线)、Surface(曲面)、Intersect(相交)、OrthogonalPlane(正交平面)等GeoGebra命令与对象;④适合高中及以上学生及数学爱好者学习圆锥几何性质与截面变换。
GeoGebra 命令及参数
Line(A, B) → fOrthogonalPlane(A, f) → aOrthogonalVector(a) → uPointIn(a) → DSurface(((m * u) * cos(v)), ((m * u) * sin(v)), u, u, -10, 10, v, 0, (2 * π)) → conIntersect(ff, gg, 0, (2 * π)) → G, KCurveCartesian(con(ff(t), t), t, 0, x(G)) → b_1Mirror(G, q) → G'CurveCartesian(con(ff(t), t), t, x(G'), (2 * π)) → b_2CurveCartesian(con(10, t), t, 0, (2 * π)) → nLine(C, J) → gCurveCartesian(con(10, t), t, 0, x(G)) → n_1Mirror(G, g) → FCurveCartesian(con(ff(t), t), t, 0, (2 * π)) → bInfiniteCone((0, 0, 0), Vector[(0, 0, 1)], α) → cLine((0, 0, 0), (0, 0, 1)) → hCircle(A, 1, Vector[(0, 1, 0)]) → dIf(β ≥ π / 2, H, I) → P_bIntersectPath(a, c) → k_1CurveCartesian(con(z(P_b), t), t, 0, (2 * π)) → jSurface(con((k * ff(t)) + ((1 - k) * z(P_b)), t), k, 0, 1, t, 0, (2 * π)) → iSurface((k * b(t)) + ((1 - k) * b(t + π)), k, 0, 1, t, 0, π) → lCircle(zAxis, P_b) → pSurface(((m * u) * cos(v)), ((m * u) * sin(v)), u, u, 0, z(P_b), v, 0, (2 * π)) → con2Intersect(ff, gg, (-92.56337323042047, 9.999999999999849)) → EIf(z(P_b) < 10, x(G), (2 * π)) → limSurface(con((k * ff(t)) + ((1 - k) * 10), t), k, 0, 1, t, 0, x(G)) → i_1Surface(con((k * z(P_b)) + ((1 - k) * 10), t), k, 0, 1, t, 0, (2 * π)) → tMidpoint(P_1, P_2) → P_3CurveCartesian(P_1 + (k * (P_3 - P_1)), k, 0, 1) → n_3CurveCartesian(P_3 + (k * (P_2 - P_3)), k, 0, 1) → n_4Surface((k * n_1(t)) + ((1 - k) * n_3((aux_2 * t) + 1)), k, 0, 1, t, 0, x(G)) → vSurface((k * n(t)) + ((1 - k) * n(t + π)), k, 0, 1, t, 0, π) → wCurveCartesian(con(10, t), t, x(G), x(G')) → n_5CurveCartesian(P_1 + (k * (P_2 - P_1)), k, 0, 1) → n_6Circle(zAxis, I) → p'Cone(p', (-z(I))) → con3, c_1, d_1Line(P_4, P_3) → f_1CurveCartesian(con(z(I), t), t, 0, x(G)) → j'_1CurveCartesian(con(z(I), t), t, x(F), (2 * π)) → j'_2Surface(((m * u) * cos(v)), ((m * u) * sin(v)), u, u, 0, z(I), v, 0, (2 * π)) → con4Line(P_3, P_4) → f'_1CurveCartesian(con(z(I), t), t, x(G), x(G')) → j'_3Surface((k * b_1(t)) + ((1 - k) * j'_1(t)), k, 0, 1, t, 0, x(G)) → v_2Translate(i_1, Vector[(k * e)]) → t_1Translate(n_1, Vector[(k * e)]) → ct_3Mirror(n_1, g) → n_2Translate(n_2, Vector[(k * e)]) → ct_4Translate(n_3, Vector[(k * e)]) → ct_5Translate(b_1, Vector[(k * e)]) → ct_1Translate(n_4, Vector[(k * e)]) → ct_6Translate(t, Vector[(k * e)]) → t'_2Translate(i, Vector[(k * e)]) → t'_3Translate(w, Vector[(k * e)]) → t'_4Translate(n, Vector[(k * e)]) → ct'_1Translate(b, Vector[(k * e)]) → ct'_2Translate(l, Vector[(k * e)]) → t'_5Surface(con((k * ff(t)) + ((1 - k) * 10), t), k, 0, 1, t, x(G'), (2 * π)) → i_2Surface((k * n_5(t)) + ((1 - k) * n_6((aux_3 * t) + aux_4)), k, 0, 1, t, x(G), x(G')) → v_1Surface((k * n_5(t)) + ((1 - k) * j'_3(t)), k, 0, 1, t, x(G), x(G')) → v_4Surface((k * b_1(t)) + ((1 - k) * b_2((aux_1 * t) + (2 * π))), k, 0, 1, t, 0, x(G)) → l_1Surface((k * b_2(t)) + ((1 - k) * j'_2(t)), k, 0, 1, t, x(G'), (2 * π)) → v_3Translate(b_2, Vector[(k * e)]) → ct_2CurveCartesian(con(z(I), t), t, 0, (2 * π)) → j'Surface((k * b(t)) + ((1 - k) * j'(t)), k, 0, 1, t, 0, (2 * π)) → oTranslate(l_1, Vector[(k * e)]) → t_2Mirror(v, f_1) → v'Translate(v, Vector[(k * e)]) → t_3Translate(v', Vector[(k * e)]) → t_4Translate(i_2, Vector[(k * e)]) → t_5IntersectPath(a, c) → e_1Focus(e_1) → L, MAxes(e_1) → g_1, h_1