四边形中点分割矩形
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①本范例演示如何通过连接四边形一对对边中点的线将其分割成一个矩形;②涉及的核心数学概念包括中点、线段、旋转、交点等;③作图要点——从下方『构造摘要』提炼用到了Polygon(多边形)、Midpoint(中点)、Segment(线段)、Intersect(交点)、Point(点)、Rotate(旋转)、Angle(角度)等GeoGebra命令/对象;④适合高中阶段学习几何作图的学生使用。
GeoGebra 命令及参数
Polygon(A, B, C, D) → poly1, a, b, c, dMidpoint(d) → FMidpoint(c) → GMidpoint(b) → HSegment(F, H) → eIntersect(OrthogonalLine[G, e], e) → JPoint(h) → LRotate(F, Angle[A, F, L], F) → F'Rotate(A, Angle[A, F, L], F) → A'Rotate(B, Angle[A, F, L], F) → B'Rotate(H, Angle[A, F, L], F) → H'_1Polygon(F', A', B', H'_1) → poly3, f', a', b', h'_1Midpoint(a') → EIntersect(OrthogonalLine[E, h'_1], h'_1) → IPoint(f) → MRotate(E, Angle[B', E, M], E) → E'Rotate(I, Angle[B', E, M], E) → I'Rotate(H'_1, Angle[B', E, M], E) → NRotate(B', Angle[B', E, M], E) → B''Polygon(E', I', N, B'') → poly4, e', i', n, b''Polygon(L, E', I, F') → poly5, l, e'_1, i, f'_1Point(g) → KRotate(F, Angle[D, F, K], F) → F'_1Rotate(H, Angle[D, F, K], F) → H'Rotate(C, Angle[D, F, K], F) → C'Rotate(D, Angle[D, F, K], F) → D'Polygon(F'_1, H', C', D') → poly2, f'_2, h', c', d'Rotate(J, Angle[D, F, K], F) → J'Rotate(G, Angle[D, F, K], F) → G'Point(p) → ORotate(G', Angle[C', G', O], G') → G''Rotate(J', Angle[C', G', O], G') → J''Rotate(H', Angle[C', G', O], G') → H''Rotate(C', Angle[C', G', O], G') → C''Polygon(G'', J'', H'', C'') → poly6, g'', j'', h'', c''Polygon(K, F'_1, J', G') → poly7, k_1, f'_3, j', g'Segment(F, H) → mSegment(G, J) → qSegment(Midpoint[Segment[A, B]], Intersect[m, OrthogonalLine[Midpoint[Segment[A, B]], m]]) → rAngle(F, Intersect[m, OrthogonalLine[Midpoint[Segment[A, B]], m]], Midpoint[Segment[A, B]]) → αAngle(H, J, G) → β