两三角平面间夹角
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①本范例演示两三角平面间夹角的计算与可视化;②涉及核心数学概念包括角度、平面、向量、立体几何及微积分;③构造要点:使用DynamicCoordinates, Rotate, Point, Plane, Angle等命令创建动态模型,通过Polygon, Line, Circle等对象辅助演示;④适合高中及以上学生及数学爱好者学习空间几何与计算几何知识。
GeoGebra 命令及参数
DynamicCoordinates(C_0, x(C_0), If[y(C_0) ≥ 1, y(C_0), 1], 0) → CRotate(C, theta, xAxis) → C'Point(xAxis) → APoint(xAxis) → BPlane(A, B, C') → dPointIn(d) → D_0Polygon(A, B, C) → t1, c, a, bLine(A, B) → fDynamicCoordinates(D_0, x(D_0), If[z(D_0) ≥ 0, y(D_0), 0], If[z(D_0) ≥ 0, z(D_0), 0]) → DPolygon(D, A, B) → t2, b_1, d_1, a_1Point(f) → PAngle(C, B, D) → βAngle(C, A, D) → αCircle(P, 1, d_1) → gIntersect(d, g) → E, FIntersect(xOyPlane, g) → G, HRay(P, E) → hRotate(D, (-theta), xAxis) → D'Segment(A, D') → jSegment(D', B) → kIf(theta ≟ 180°, CircumcircleArc[D', (x(D'), 0, y(D')), D], CircleArc[Q, D, D', xOyPlane]) → eRay(P, If[x(B) > x(A), G, H]) → iAngle(If[x(B) > x(A), G, H], P, E) → εAngle(E, P, P + (-1, 0, 0)) → γAngle(P + (1, 0, 0), P, If[x(B) > x(A), G, H]) → δ