动态圆与弦关系演示
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①本范例动态演示圆的直径、弦及两条特殊线段(T/Y线段)之间的关系;②涉及核心数学概念包括圆的性质、弦、特殊线段、角度、中点、旋转与变换;③作图要点运用了Circle(圆)、Point(点)、Line(线)、Intersect(交点)、Semicircle(半圆)、OrthogonalLine(垂线)、Dilate(缩放)、Segment(线段)、Angle(角度)、Midpoint(中点)、Rotate(旋转)等GeoGebra命令;④适合高中数学教学,用于理解圆与几何变换。
GeoGebra 命令及参数
Circle(A, B) → cPoint(c) → CLine(C, A) → fIntersect(c, f, 2) → DSemicircle(C, D) → dSemicircle(D, C) → ePoint(e) → EPoint(d) → FLine(E, F) → gIntersect(f, g) → GOrthogonalLine(C, g) → hIntersect(g, h) → HOrthogonalLine(D, g) → iIntersect(g, i) → IDilate(C, If[0 < a ≤ 1, 1 - a, 0], D) → C'Segment(C, C') → jDilate(E, If[1 < a ≤ 2, 2 - a, 0], H) → E'Segment(E, E') → kDilate(F, If[1 < a ≤ 2, 2 - a, 0], I) → F'Segment(F, F') → lDilate(I, If[2 < a ≤ 3, 3 - a, 0], G) → I'Dilate(H, If[2 < a ≤ 3, 3 - a, 0], G) → H'Segment(H, H') → mSegment(I, I') → nDilate(C, If[3 < a ≤ 4, 4 - a, 0], H) → C'_1Dilate(D, If[3 < a ≤ 4, 4 - a, 0], I) → D'Angle(G, H, C) → αSegment(D, D') → pSegment(C, C'_1) → qMidpoint(E, F) → JAngle(E, I, D) → βRotate(E, If[4.5 < a ≤ 5.5, ((a - 4.5) * π), π], J) → E'_1Rotate(E', If[4.5 < a ≤ 5.5, ((a - 4.5) * π), π], J) → E''Rotate(E, If[5 < a ≤ 6, ((a - 5) * π), π], J) → E'_2Rotate(E', If[5 < a ≤ 6, ((a - 5) * π), π], J) → E''_1Segment(E'_2, E''_1) → k'