确定三角函数的精确值
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①本范例演示如何通过几何作图确定三角函数的精确值;②涉及核心数学概念包括三角函数、等边三角形、圆、角度测量;③作图要点提炼自 GeoGebra 命令:Intersect(交点)、Point(点)、Circle(圆)、Segment(线段)、Distance(距离)、Angle(角度)、Vector(向量)、Polygon(多边形)、Line(直线)、Mirror(镜像);④适合高中数学教学,用于帮助学生理解三角函数值的几何意义和计算方法。
GeoGebra 命令及参数
Intersect(xAxis, yAxis) → OPoint(xAxis) → ECircle(O, E) → c_1Point(c_1) → PSegment(O, P) → aDistance(P, A_1) → bAngle(E, O, P) → αSegment(A_1, (x(A_1), 0)) → fSegment(A_2, (x(A_2), 0)) → gSegment(B_2, B_1) → hSegment(C_2, C_1) → iVector(O, P) → uVector(P, (x(P), 0)) → vVector(P, (0, y(P))) → wPoint(u) → ASegment(A, C_2) → eSegment(A, B_2) → jSegment(A, A_2) → kSegment(A, A_3) → lSegment(A, B_3) → mSegment(A, C_3) → nSegment(A, C_4) → pSegment(A, B_4) → qSegment(A, A_4) → rSegment(A, A_1) → s_1Segment(A, B_1) → tSegment(A, C_1) → a_1Polygon(P, (x(P), 0), A) → poly1, a_2, B, b_1Polygon((abs(x(P)), abs(y(P))), A, (abs(x(P)), 0)) → poly2, d_1, e_1, a_3Point(d_1) → CLine(C, C_1) → sPoint(e) → DLine(C, D) → cPoint(j) → FLine(C, F) → f_1Point(k) → GLine(C, G) → g_1Point(l) → HLine(C, H) → h_1Point(m) → ILine(C, I) → i_1Intersect(c_1, c) → J, KIntersect(c_1, f_1) → L, MIntersect(c_1, h_1) → R, TIntersect(c_1, i_1) → U, VIntersect(c_1, s) → Z, D_1Segment(M, L) → l_1Segment(V, U) → m_1Segment(D_1, Z) → n_1Segment(K, J) → p_1Segment(T, R) → k_1Mirror(R, xAxis) → R'Point(l_1) → QLine(R', Q) → j_1Intersect(c_1, j_1) → E_1, F_1Segment(F_1, E_1) → q_1