圆内接角探索
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①本范例演示了圆内接角定理的几何直观,通过动态演示证明圆心角与圆周角的关系;②涉及核心数学概念包括圆、角、相交线、切线、旋转、相似三角形等;③作图要点提炼自GeoGebra命令:使用Circle(圆)、Point(点)、CircleArc(圆弧)、Segment(线段)、Angle(角)、Rotate(旋转)、Intersect(交点)、CircleSector(扇形)、Dilate(缩放)、Vector(向量)、Line(直线)、Translate(平移);④适合高中数学几何教学,用于加深学生对圆内接角定理的理解和应用。
GeoGebra 命令及参数
Circle(A, B) → cPoint(c) → CPoint(c) → DCircleArc(A, D, C) → dPoint(d) → EPoint(d) → FCircleArc(A, C, D) → eSegment(A, C) → aSegment(A, D) → bSegment(E, C) → fSegment(E, D) → gSegment(F, C) → hSegment(F, D) → iAngle(C, A, D) → αRotate(C, α / 2, A) → C'Angle(C, A, C') → βSegment(A, C') → jCircle(E, (0.25 * Distance[A, B])) → kIntersect(k, f, 1) → GIntersect(k, g, 1) → HCircle(F, (0.25 * Distance[A, B])) → pIntersect(p, h, 1) → JIntersect(p, i, 1) → KCircleSector(E, G, H) → qCircleSector(F, J, K) → rDilate(E, If[0 < l ≤ 1, 1 - l, 0], A) → E'Vector(E, E') → uLine(E, a) → mIntersect(k, m, 2) → LAngle(L, E, G) → γDilate(E, If[2 < l ≤ 3, 3 - l, 0], A) → E'_1Vector(E, E'_1) → vLine(E, j) → nIntersect(k, n, 2) → MAngle(M, E, G) → δCircle(A, (0.25 * Distance[A, B])) → tIntersect(t, a, 1) → NIntersect(t, j, 1) → OIntersect(t, c, 1) → IIntersect(t, b) → P,CircleArc(A, N, P) → c_1Point(d) → QSegment(Q, C) → a_1Segment(Q, D) → b_1Dilate(E, If[0 < l ≤ 1, 1 - l, 0], F) → E'_2Dilate(E, If[0 < l ≤ 1, 1 - l, 0], Q) → E'_3Vector(E, E'_2) → wVector(E, E'_3) → sTranslate(q, w) → q'Translate(q, s) → q'_1Line(E, i) → d_1Intersect(k, d_1) → R, SAngle(H, E, S) → εRotate(q', ((l - 1) * ε), F) → q''Line(E, a_1) → e_1Intersect(k, e_1) → T, UAngle(U, E, G) → ζRotate(q'_1, ((-(l - 1)) * ζ), Q) → f_1Segment(C, D) → g_1