不同象限中三角比的值
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本范例展示了角度在不同象限时三角比(正弦、余弦、正切)的符号和数值变化。通过旋转和构造几何图形,学生可以直观理解三角比在各个象限中的变化规律。使用了Circle, Point, Tangent, Rotate, Line, Intersect, Angle, Segment, OrthogonalLine等GeoGebra命令。适合初中及以上学生学习三角函数。
GeoGebra 命令及参数
Circle(A, 1) → cPoint(c) → BTangent(B, c) → a_2,Rotate(B, β, A) → CLine(A, C) → bIntersect(a_2, b) → DAngle(B, A, C) → αSegment(B, D) → fOrthogonalLine(C, xAxis) → gOrthogonalLine(C, yAxis) → hIntersect(h, yAxis) → FIntersect(g, xAxis) → HSegment(F, C) → iSegment(C, H) → jSegment(A, F) → kSegment(A, H) → lPoint(c) → JTangent(J, c) → m,Line(A, C) → dTangent(J, c) → e,Intersect(e, d) → ESegment(E, C) → pSegment(C, A) → qSegment(J, E) → rTangent(C, c) → s,Intersect(yAxis, s) → GSegment(C, G) → tSegment(A, G) → a_1Tangent(C, c) → b_1,Intersect(b_1, xAxis) → ISegment(C, I) → c_1Segment(A, I) → d_1Segment(C, D) → e_1