六分仪
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通过调整六分仪,使太阳的像与地平线的像重合。红角表示仰角,此范例演示了仰角与地平线的关系,涉及三角函数和角度概念。使用了交点、圆、旋转、角度、圆弧、线段、线、中点、向量等GeoGebra命令。适合初中及以上学生学习三角函数和几何作图。
GeoGebra 命令及参数
Intersect(xAxis, yAxis) → OCircle(O, R) → sextantCirclePoint(sextantCircle) → zeroDegreesRotate(zeroDegrees, 30*°, O) → zeroDegrees'_1Angle(zeroDegrees, O, zeroDegrees'_1) → thirtyDegrees2Rotate(zeroDegrees, 330*°, O) → zeroDegrees'Angle(zeroDegrees', O, zeroDegrees) → thirtyDegrees1CircleArc(O, zeroDegrees', zeroDegrees'_1) → sixtantArcSegment(O, zeroDegrees') → sixtantSegment1Point(sixtantArc) → ASegment(O, A) → sixtantSegment2Point(sixtantArc) → MovablePointPoint(sixtantSegment1) → mirrorBaseCircle(mirrorBase, r) → cLine(mirrorBase, yAxis) → verticalMirrorLineIntersect(c, verticalMirrorLine, 2) → verticalIntersectPointRotate(verticalIntersectPoint, mirrorAngle, mirrorBase) → verticalIntersectPoint'Angle(verticalIntersectPoint, mirrorBase, verticalIntersectPoint') → mAngleCircle(O, r / 2) → dSegment(mirrorBase, verticalIntersectPoint') → mirror1Midpoint(mirrorBase, verticalIntersectPoint') → mirrorCentreLine(mirrorCentre, xAxis) → horizonLineSegment(O, mirrorCentre) → bMidpoint(O, mirrorCentre) → BVector(O, B) → uOrthogonalLine(mirrorCentre, mirror1) → mirrorNormalIntersect(c, mirrorNormal, 1) → CAngle(C, mirrorCentre, O) → angleToNormalAngle(MovablePoint, O, zeroDegrees'_1) → angleMovablePoint(d) → DRotate(D, mirrorAngle - angleMovable, O) → M1Angle(D, O, M1) → αLine(M1, O) → eIntersect(d, e, 2) → M2Segment(M2, M1) → mirror2OrthogonalLine(O, mirror2) → mirror2NormalIntersect(d, mirror2Normal, 2) → EAngle(E, O, mirrorCentre) → βRotate(E, (-β), O) → E'Angle(E', O, E) → γRay(O, E') → fSegment(O, MovablePoint) → gIntersect(d, g, 1) → FSegment(F, MovablePoint) → hPoint(horizonLine) → HorizonPointLine(HorizonPoint, yAxis) → aRay(G, H) → iPoint(i) → SunPointPoint(f) → IPoint(f) → JVector(I, J) → vPoint(horizonLine) → KCircle(SunPoint, r) → kSegment(SunPoint, O) → jIntersect(k, j, 1) → LMirror(HorizonPoint, yAxis) → HorizonPoint'Line(HorizonPoint', yAxis) → mPoint(horizonLine) → NVector(mirrorCentre, N) → zPoint(horizonLine) → PIntersect(f, i) → QVector(SunPoint, Q) → pTranslate(HorizonPoint', Vector[(-p)]) → HorizonPoint''Vector(HorizonPoint', HorizonPoint'') → qPoint(horizonLine) → SPoint(horizonLine) → TPoint(horizonLine) → UPoint(horizonLine) → VVector(U, P) → nPoint(horizonLine) → MVector(M, K) → wSegment(K, S) → lSegment(N, T) → sSegment(P, V) → tRotate(zeroDegrees'_1, 350*°, O) → WAngle(W, O, zeroDegrees'_1) → δRotate(W, 350*°, O) → W'Angle(W', O, W) → εRotate(W', 350*°, O) → W''Angle(W'', O, W') → ζRotate(W'', 350*°, O) → W'''Angle(W''', O, W'') → ηRotate(W''', 350*°, O) → ZAngle(Z, O, W''') → θSegment(W, O) → a_1Segment(W', O) → b_1Segment(W'', O) → c_1Segment(W''', O) → d_1Segment(Z, O) → e_1Point(xAxis) → A_1Angle(SunPoint, O, A_1) → ιCircle(MovablePoint, 1.5) → f_1Line(O, MovablePoint) → g_1Intersect(f_1, g_1, 2) → textPoint