平面图形面积:用几何变换构造与分解
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本范例通过几何变换与作图分解,演示如何比较或计算不同“纯形/平面图形”的面积。核心数学概念包括多边形面积、边与中点的几何关系、以及围绕点的旋转、镜像、平移与缩放(同构/相似变换)对面积的影响。构造上使用了 GeoGebra 的基本几何工具生成与关联点:Point、Line、Segment、Intersect(求交)、Midpoint(求中点)与 Polygon(多边形);再用 OrthogonalLine(作垂线)、Vector(向量表示平移方向)、Rotate(旋转)、Translate(平移)、Mirror(关于直线镜像)、Dilate(以点为中心缩放)把图形复制到新位置以实现面积对应与对比。对象包括大量由构造得到的关键点与派生图形(如 A、B、C、D、E/F/G、以及对应的 E'、I'、t1'、i'、e' 等)。适合中学到大学基础几何教学,用于面积不变量、变换理解与几何作图训练,也可作为竞赛几何的可视化辅助。
GeoGebra 命令及参数
Segment(A, B) → fOrthogonalLine(A, f) → gOrthogonalLine(B, f) → hPoint(h) → CLine(C, f) → iIntersect(g, i) → DMidpoint(E, A) → FMidpoint(B, E) → GOrthogonalLine(E, f) → jIntersect(f, j) → HLine(F, f) → kIntersect(j, k) → IPolygon(E, F, I) → t1, i_1, e, f_1Polygon(I, G, E) → t2, e_1, i_2, g_1Polygon(F, A, B, G) → q1, f_2, a, b, g_2Rotate(E, (π * c / 2), F) → E'Rotate(F, (π * c / 2), F) → F'Rotate(I, (π * c / 2), F) → I'Polygon(E', F', I') → t1', i', e', f'Rotate(I, ((-π) * c / 2), G) → I'_1Rotate(G, ((-π) * c / 2), G) → G'Rotate(E, ((-π) * c / 2), G) → E'_1Polygon(I'_1, G', E'_1) → t2', e'_1, i'_1, g'Segment(D, C) → lPoint(f) → JSegment(C, J) → mLine(A, m) → nIntersect(l, n) → KOrthogonalLine(K, f) → pIntersect(p, f) → LPolygon(K, A, L) → t3, l_1, k_1, a_1Polygon(L, J, C, K) → q2, l_2, j_1, c_1, k_2Vector(A, V) → uTranslate(K, u) → K'Translate(A, u) → A'Translate(L, u) → L'Polygon(K', A', L') → t3', l', k', a'Point(l) → MPoint(l) → NMidpoint(M, A) → OMidpoint(N, B) → POrthogonalLine(P, f) → qOrthogonalLine(O, f) → rIntersect(r, f) → QIntersect(q, f) → RPolygon(M, O, Q, R, P, N) → poly1, m_1, o_1, q_1, r_1, p_1, n_1Polygon(O, A, Q) → t4, q_2, o_2, a_2Polygon(R, B, P) → t5, p_2, r_2, b_1Rotate(R, (π * c / 2), P) → R'Rotate(B, (π * c / 2), P) → B'Rotate(P, (π * c / 2), P) → P'Polygon(R', B', P') → t5', p', r', b'Rotate(O, ((-π) * c / 2), O) → O'Rotate(A, ((-π) * c / 2), O) → A'_1Rotate(Q, ((-π) * c / 2), O) → Q'Polygon(O', A'_1, Q') → t4', q', o', a'_1Mirror(A, D) → A'_2Mirror(B, C) → B'_1Midpoint(A'_2, B'_1) → SMidpoint(A, B) → TMidpoint(D, C) → UPolygon(S, D, U) → t6, u_1, s_1, d_1Polygon(S, U, C) → t7, c_2, s_2, u_2Polygon(D, T, U) → t8, u_3, d_2, tPolygon(T, C, U) → t9, u_4, t_1, c_3Rotate(S, ((π * 3) * c / 4), D) → S'Rotate(D, ((π * 3) * c / 4), D) → D'Rotate(U, ((π * 3) * c / 4), D) → U'Rotate(S, (((-π) * 3) * c / 4), C) → S'_1Rotate(U, (((-π) * 3) * c / 4), C) → U'_1Rotate(C, (((-π) * 3) * c / 4), C) → C'Midpoint(A'_2, D) → WMidpoint(B'_1, C) → ZMidpoint(T, Z) → A_1Midpoint(T, W) → B_1Midpoint(S, W) → C_1Midpoint(S, Z) → D_1Segment(S, T) → h_1Segment(C_1, D_1) → h_2Segment(B_1, A_1) → j_2Intersect(j_2, h_1) → E_1Intersect(h_1, h_2) → F_1Polygon(C_1, F_1, S) → t10, s_3, m_2, n_2Polygon(F_1, D_1, S) → t11, s_4, t_2, b_2Polygon(T, A_1, E_1) → t12, e_2, t_3, f_3Polygon(E_1, B_1, T) → t13, t_4, g_3, h_3Segment(W, Z) → i_3Intersect(i_3, h_1) → G_1Polygon(F_1, G_1, Z, D_1) → q3, j_3, k_3, z_1, l_3Polygon(C_1, W, G_1, F_1) → q4, m_3, w, n_3, p_3Polygon(E_1, A_1, Z, G_1) → q5, q_3, r_3, z_2, a_3Polygon(B_1, E_1, G_1, W) → q6, b_3, d_3, e_3, w_1Rotate(C_1, (π * c / 2), C_1) → H_1Rotate(F_1, (π * c / 2), C_1) → I_1Rotate(S, (π * c / 2), C_1) → S'_2Polygon(H_1, I_1, S'_2) → t10', s'_2, f_4, g_4Rotate(F_1, ((-π) * c / 2), D_1) → J_1Rotate(D_1, ((-π) * c / 2), D_1) → K_1Rotate(S, ((-π) * c / 2), D_1) → S'_3Polygon(J_1, K_1, S'_3) → t11', s'_3, h_4, i_4Rotate(T, (π * c / 2), A_1) → T'Rotate(A_1, (π * c / 2), A_1) → L_1Rotate(E_1, (π * c / 2), A_1) → M_1Polygon(T', L_1, M_1) → t12', j_4, t', k_4Rotate(E_1, ((-π) * c / 2), B_1) → N_1Rotate(B_1, ((-π) * c / 2), B_1) → O_1Rotate(T, ((-π) * c / 2), B_1) → T'_1Polygon(N_1, O_1, T'_1) → t13', t'_1, l_4, m_4Midpoint(D, S) → R_1Midpoint(T, C) → S_1Midpoint(S, C) → T_1Midpoint(D, T) → U_1Dilate(R_1, If[0 < c ≤ 1, 1 - c, 0], S_1) → V_1Vector(R_1, V_1) → v_2Dilate(T_1, If[1 < c ≤ 2, 2 - c, 0], U_1) → W_1Vector(T_1, W_1) → w_2Translate(S, v_2) → S'_4Translate(D, v_2) → D'_1Translate(U, v_2) → U'_2Polygon(S'_4, D'_1, U'_2) → t6', u'_2, s'_4, d'_1Translate(S, w_2) → S'_5Translate(U, w_2) → U'_3Translate(C, w_2) → C'_1Polygon(S'_5, U'_3, C'_1) → t7', c'_1, s'_5, u'_3
AI 绘图提示语参考
请绘制一个由多个平面多边形组成的图形,展示通过旋转、反射、翻译和缩放等几何变换对面积的影响。图形中包含原始多边形及其变换后的副本,这些副本通过旋转和翻译放置在特定位置,以体现面积对应关系。关键对象包括点、线段和多边形,它们通过相交、垂直线和中点构造连接。图形应清晰展示变换后的多边形与原始多边形之间的对应关系,适合用于几何教学和面积推理。
以上提示语为根据原始绘图命令整理而来,仅供参考。