三角形四心共点演示
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①本范例演示了三角形中四个重要点(重心、垂心、内心、外心)的共点性;②涉及的核心数学概念包括三角形的几何性质、四心定理、解析几何作图;③作图要点提炼自GeoGebra命令:使用Line(线)、Segment(线段)、OrthogonalLine(垂线)、Intersect(交点)、Midpoint(中点)、Angle(角)、AngularBisector(角平分线)、LineBisector(线段平分线)等命令,构建了三角形的顶点、边、高、中线、角平分线及圆;④适合高中及以上数学学习者,用于理解三角形核心几何性质及作图方法。
GeoGebra 命令及参数
Line(A, B) → LineABLine(B, C) → LineBCLine(C, A) → SegACSegment(B, A) → SegABSegment(A, C) → SegAC_1Segment(C, B) → SegBCOrthogonalLine(A, LineBC) → fOrthogonalLine(C, LineAB) → gOrthogonalLine(B, SegAC) → hIntersect(SegAC, h) → DIntersect(g, LineAB) → FIntersect(LineBC, f) → GSegment(B, D) → AltitudeBDSegment(A, G) → AltitudeAGSegment(F, C) → AltitudeFCMidpoint(B, C) → HMidpoint(B, A) → IMidpoint(A, C) → JSegment(I, C) → MedianCISegment(B, J) → MedianBJSegment(A, H) → MedianAHAngle(A, G, B) → αAngle(B, D, C) → βAngle(C, F, A) → γSegment(A, I) → AISegment(I, B) → BISegment(B, H) → BHSegment(H, C) → CHSegment(A, J) → AJSegment(J, C) → CJIntersect(MedianCI, MedianBJ) → EIntersect(AltitudeBD, AltitudeAG) → KAngularBisector(B, C, A) → iAngularBisector(C, A, B) → jAngularBisector(A, B, C) → kIntersect(j, LineBC) → LIntersect(LineAB, i) → MIntersect(k, SegAC) → PSegment(B, P) → AngBisBPSegment(C, M) → AngBisCMSegment(L, A) → AngBisALIntersect(AngBisBP, AngBisCM) → InCenterNLineBisector(SegAC_1) → lLineBisector(SegAB) → mLineBisector(SegBC) → nIntersect(LineBC, n) → NIntersect(LineAB, m) → OIntersect(SegAC, l) → QIntersect(l, m) → RSegment(R, Q) → PerpBisPQSegment(R, N) → PerpBisRNSegment(R, O) → PerpBisORAngle(R, Q, C) → δAngle(R, N, B) → εAngle(R, O, A) → ζLine(N, R) → pLine(Q, R) → qLine(R, O) → r