三角形内角和动画演示
几何画板及绘图内容加载中,请稍等……
①本范例通过动态演示证明三角形的内角和恒等于180°;②涉及核心数学概念:三角形内角、几何证明、平行线性质;③作图要点:使用Polygon、Midpoint、Segment、OrthogonalLine、Intersect、Mirror、Angle等GeoGebra命令构建三角形及辅助线,通过动画展示角度变化;④适合初中及以上学生学习几何定理证明,也可用于数学教学演示。
GeoGebra 命令及参数
Polygon(C, B, A) → poly1, a, c, bMidpoint(a) → DMidpoint(c) → ESegment(D, E) → dOrthogonalLine(D, b) → fOrthogonalLine(E, b) → gIntersect(f, b) → FIntersect(g, b) → GSegment(F, D) → f'Segment(G, E) → g'Mirror(B, d) → B'Segment(B, B') → hPolygon(E, D, B'') → poly2, b_2, e_2, d_2Polygon(G, E, A'') → poly3, a_3, g_3, e_3Polygon(F, D, C'') → poly4, c_4, f_4, d_4Polygon(E, D, B) → poly5, b_5, e_5, d_5Polygon(G, E, A) → poly6, a_6, g_6, e_6Polygon(F, D, C) → poly7, c_7, f_7, d_7Angle(E, B'', D) → βAngle(E, B, D) → β_1Angle(G, A'', E) → αAngle(G, A, E) → α_1Angle(D, C'', F) → γAngle(D, C, F) → γ_1