切线与半径的关系

GeoGebra 命令及参数

1. Circle(O, radius) → circ
2. Point(circ) → StartPt
3. Sequence(Rotate[StartPt, i°, O], i, 0, 360, 1) → allPoints
4. Point(allPoints) → A
5. Point(allPoints) → B
6. LaTeX((((("\text{" * MainInstruc) * "\\") * SpecInstruc) * "}")) → allInstruc
7. Segment(O, A) → segOA
8. Circle(O, radius + 0.75) → labelCircle
9. Line(A, B) → secant
10. Tangent(B, circ) → tangentLine,
11. Angle(Line[B, O], tangentLine) → tangentAngle
12. Segment(O, B) → segOB
13. Polygon({(left, top), (left, bottom), (right, bottom), (right, top)}) → viewbox
14. Point(tangentLine) → TangentC
15. If(Angle[O, A, C'] < 180°, Angle[O, A, C'], Angle[C', A, O]) → OAC'
16. Point(tangentLine) → TangentC'
17. Angle(TangentC', A, O) → tangentAngle2
18. If(A ≠ B, ("" * OAC'), "90°") → angleSize