欧拉线与三角形中心
几何画板及绘图内容加载中,请稍等……
①本范例演示了三角形欧拉线及其上的五个重要中心点:重心、外心、垂心、内心和九点圆心。②涉及的核心数学概念包括:重心、外心、垂心、内心、九点圆、欧拉线、向量、解析几何。③作图要点:使用Polygon命令构造三角形,用Circle命令画外接圆和九点圆,通过Intersect命令求交点,用Midpoint命令找中点,Line命令画直线,OrthogonalLine命令画垂线,Segment命令画线段。④适合高中及以上学生学习和理解三角形几何性质,也可用于竞赛数学和几何作图教学。
GeoGebra 命令及参数
Polygon(A, B, C) → poly1, c, a, bCircle(C, D) → dCircle(B, E) → eCircle(A, F) → fIntersect(d, b, 1) → GIntersect(d, a, 1) → HIntersect(e, a, 1) → IIntersect(e, c, 1) → JIntersect(f, c, 1) → KIntersect(f, b, 1) → LMidpoint(L, K) → MMidpoint(J, I) → NMidpoint(H, G) → OLine(C, O) → gLine(B, N) → hLine(A, M) → iIntersect(g, h) → lncenterIntersect(g, i) → Incenter_.Intersect(h, i) → IncenterOrthogonalLine(Incenter, c) → jOrthogonalLine(Incenter, a) → kOrthogonalLine(Incenter, b) → lIntersect(j, c) → SCircle(Incenter, S) → pOrthogonalLine(Incenter_., c) → mOrthogonalLine(Incenter_., a) → nOrthogonalLine(Incenter_., b) → qIntersect(m, c) → TCircle(Incenter_., T) → rOrthogonalLine(lncenter, c) → sOrthogonalLine(lncenter, b) → tOrthogonalLine(lncenter, a) → f_1Intersect(s, c) → UCircle(lncenter, U) → c_1Midpoint(b) → Pm_3Midpoint(a) → Pm_2Midpoint(c) → Pm_1Line(C, Pm_1) → g_1Line(Pm_2, A) → h_1Line(Pm_3, B) → i_1Intersect(g_1, h_1) → CentroidOrthogonalLine(C, c) → j_1OrthogonalLine(A, a) → k_1OrthogonalLine(B, b) → l_1Intersect(j_1, k_1) → OrthocenterIntersect(l_1, b) → Ph_3Intersect(j_1, c) → Ph_1Intersect(k_1, a) → Ph_2Segment(Orthocenter, C) → m_1Segment(Orthocenter, B) → n_1Segment(Orthocenter, A) → p_1Midpoint(n_1) → P_H2Midpoint(p_1) → P_H1Midpoint(m_1) → P_H3OrthogonalLine(Pm_2, a) → q_1OrthogonalLine(Pm_1, c) → r_1OrthogonalLine(Pm_3, b) → s_1Intersect(q_1, r_1) → CircumcenterCircle(Circumcenter, A) → CirumcircleMidpoint(Orthocenter, Circumcenter) → NinePointCenterCircle(NinePointCenter, Pm_1) → NinePointCircleLine(Circumcenter, Orthocenter) → t_1Line(Circumcenter, Orthocenter) → TheEulerLine