旋转对称性演示 by Irina Boyadzhiev
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①本范例演示了图形的旋转对称性现象,通过旋转图形展示其对称特性;②涉及的核心数学概念包括对称性、旋转角度、多边形构造;③作图要点——使用了GeoGebra命令/对象:Corner(顶点)、Midpoint(中点)、Polygon(多边形)、Segment(线段)、Intersect(交点)、Rotate(旋转)、Angle(角度)、Point(点);④适合初中及以上学生学习几何变换和对称性知识,也可用于数学教学演示。
GeoGebra 命令及参数
Corner(pic1, 1) → LBMidpoint(LB, RT) → MMPolygon(A, B, 3) → poly1, a, a_1, b, CMidpoint(a) → DMidpoint(a_1) → ESegment(A, E) → cSegment(D, C) → dIntersect(c, d) → FRotate(A, α, F) → A'Rotate(B, α, F) → B'Rotate(C, α, F) → C'Polygon(A', B', C') → poly1', c', a', b'Polygon(G, H, I, J) → poly2, g, h, i, jSegment(G, I) → eSegment(J, H) → fIntersect(e, f) → KRotate(G, α, K) → G'Rotate(H, α, K) → H'Rotate(I, α, K) → I'Rotate(J, α, K) → J'Polygon(G', H', I', J') → poly2', g', h', i', j'Rotate(pic1, α, L) → pic1'Polygon(M, N, 5) → poly3, m_1, n, p, q, r, O, P, QMidpoint(p) → RMidpoint(n) → SSegment(Q, S) → sSegment(M, R) → tIntersect(t, s) → TRotate(M, α, T) → M'Rotate(N, α, T) → N'Rotate(O, α, T) → O'Rotate(P, α, T) → P'Rotate(Q, α, T) → Q'Polygon(M', N', O', P', Q') → poly3', m', n', o', p', q'Angle(B, A, C) → βAngle(B', A', C') → γAngle(H, G, J) → δAngle(H', G', J') → εSegment(G', I') → b_1Segment(J', H') → c_1Intersect(c_1, b_1) → UAngle(N', M', Q') → ζAngle(N, M, Q) → ηSegment(T, M') → d_1Point(d_1) → VSegment(V, N') → e_1Segment(V, O') → f_1Segment(V, P') → g_1Segment(V, Q') → h_1Corner(pic1, 2) → RB