垂直抛物线:焦点、准线与焦点弦
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①本范例演示垂直抛物线的几何性质,包括焦点、准线、焦点弦的动态关系;②涉及核心数学概念:抛物线定义、焦点-准线距离、焦点弦长度、解析几何;③作图要点:使用 GeoGebra 命令 Point(点)、OrthogonalLine(垂线)、Intersect(交点)、Segment(线段)、Angle(角度)、Distance(距离)、Line(直线)、Midpoint(中点)等构建抛物线及其相关元素;④适合高中解析几何教学或数学爱好者探索抛物线性质。
GeoGebra 命令及参数
Point(Directrix) → RandomPointonDirectrixOrthogonalLine(RandomPointonDirectrix, Directrix) → bIntersect(c, b) → B, DSegment(Focus, B) → dPoint(Directrix) → CAngle(B, RandomPointonDirectrix, C) → αSegment(RandomPointonDirectrix, B) → eDistance(Focus, B) → distanceFocusBDistance(RandomPointonDirectrix, B) → distanceABSegment(Focus, D) → fSegment(RandomPointonDirectrix, D) → gAngle(C, RandomPointonDirectrix, D) → βDistance(Focus, D) → distanceFocusDDistance(D, RandomPointonDirectrix) → distanceDRandomPointonDirectrixSegment(Focus, Vertex) → iOrthogonalLine(Vertex, Directrix) → jIntersect(j, Directrix) → ASegment(A, Vertex) → lDistance(Focus, Vertex) → distanceFocusVertexDistance(Vertex, A) → distanceVertexALine(Focus, Directrix) → mIntersect(c, m) → E, FSegment(E, F) → nSegment(E, F) → qDistance(E, F) → distanceEFMidpoint(E, F) →Distance(Vertex, Focus) → distanceVertexFocusMidpoint(Vertex, Focus) →Distance(Vertex, A) → aMidpoint(Vertex, A) →