相似三角形构造与性质探究
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① 本范例通过GeoGebra动态演示了相似三角形的构造过程,直观展示两个三角形对应角相等、对应边成比例的性质。② 核心数学概念包括相似三角形的判定与性质、比例关系、以及通过平移、旋转、缩放等变换保持形状不变的特点。③ 作图要点:从构造摘要可见,使用了Mirror(镜像)、Ray(射线)、Point(点)、Line(直线)、Intersect(交点)、Polygon(多边形)、Segment(线段)、Dilate(缩放)、OrthogonalLine(垂线)、Angle(角)、Distance(距离)等GeoGebra命令,创建了多个三角形(poly1、poly2、poly3)及辅助线,通过缩放和镜像操作生成相似图形。④ 适合初中高年级或高中低年级学生学习相似三角形概念,也可用于几何作图教学,帮助学生理解动态几何中相似关系的保持。
GeoGebra 命令及参数
Mirror(G, F) → G'Ray(F, G') → lPoint(l) → JLine(H, F) → q_2Line(G, H) → l_2Line(J, l_2) → p_2Intersect(q_2, p_2) → C_1Line(A, B) → b_1Polygon(C, A, B) → poly1, b, c, a_2Ray(A, C) → gPoint(g) → DLine(D, a_2) → h_2Intersect(h_2, b_1) → ZPolygon(F, G, H) → poly2, h_1, f_1, g_1Ray(A, B) → fSegment(D, A) → hSegment(E, A) → iSegment(D, E) → jMirror(H, F) → H'Ray(F, H') → kSegment(I, F) → mSegment(F, J) → nSegment(J, I) → pPolygon(A, D, E) → poly3, e, a_1, dPolygon(F, J, I) → poly4, i_1, f_2, j_1Polygon(K, L, M) → poly5, m_1, k_1, l_1Dilate(M, o, M) → M'Dilate(K, o, Scale) → K'Dilate(L, o, Scale) → L'Dilate(M, o, Scale) → M'_1Polygon(K', L', M'_1) → poly5', m'_1, k', l'Segment(O, P) → qSegment(O, Q) → rSegment(P, Q) → sDilate(O, 1 / 3, Q) → O'Line(O', s) → tIntersect(q, t) → RSegment(R, O') → n_1Segment(O, O') → p_1Segment(O', Q) → q_1Segment(R, P) → r_1Segment(R, O) → s_1Line(A, C) → t_1Line(F, p) → c_1Line(G, m) → d_1Intersect(d_1, c_1) → SLine(T, U) → e_1Point(e_1) → VOrthogonalLine(V, e_1) → g_2Point(g_2) → WSegment(W, U) → i_2Segment(U, V) → j_2Segment(W, V) → k_2OrthogonalLine(V, i_2) → m_2OrthogonalLine(V, j_2) → n_2Intersect(m_2, i_2) → A_1Segment(V, A_1) → r_2Intersect(i_2, r_2) → B_1Angle(V, U, W) → βAngle(U, W, V) → γAngle(W, A_1, V) → δAngle(U, A_1, V) → εAngle(W, V, A_1) → ζAngle(U, V, A_1) → ηDistance(W, i_2) → distanceWi2Distance(A_1, W) → distanceA1WDistance(A_1, U) → distanceA1ULine(G, F) → s_2