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Sine and Cosine with Unit Circle

Sine and Cosine with Unit Circle
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2018-02-09 18:48
CircleVectorTrigonometryCoordinate GeometryGeometric Construction
This example dynamically demonstrates the relationship between the coordinates of a point on the unit circle and its angle, visually showcasing the geometric meaning of sine and cosine functions. Core math concepts include the unit circle, trigonometric functions, coordinate geometry, angles, and vectors. Construction highlights involve GeoGebra commands/objects like Segment, Intersect, Circle, Vector, Line, and Angle to build the unit circle, sine and cosine lines, and vectors. Suitable for high school students learning about trigonometric definitions and unit circle applications.

GeoGebra Commands & Parameters

  1. Segment((-1, sin(Θ)), (1, sin(Θ))) → segSin
  2. Segment((cos(Θ), -1), (cos(Θ), 1)) → segCos
  3. Intersect(segSin, segCos) → Pr
  4. Circle((0, 0), 1) → uc
  5. Vector((1.5 + Θ / 2, 0), (1.5 + Θ / 2, sin(Θ))) → vecSin
  6. Vector((1, 0), (1, sin(Θ))) → vecSin2
  7. Vector((0, 1), (cos(Θ), 1)) → vecCos2
  8. Vector((1.5 + Θ / 2, 0), (1.5 + Θ / 2, cos(Θ))) → vecCos
  9. Segment((1.3, 0), (4.841592653589793, 0)) → xa
  10. Segment((-1.1, 0), (1.1, 0)) → cx
  11. Segment((0, -1.1), (0, 1.1)) → cy
  12. Line((Θ / 2 + 1.5, 0), (Θ / 2 + 1.5, 1)) → e
  13. Segment((0, 0), (cos(Θ), sin(Θ))) → segRadius
  14. Segment((cos(Θ), 1), (1.5 + Θ / 2, 1)) → segCosCon1
  15. Segment((1.5 + Θ / 2, 1), (1.5 + Θ / 2, cos(Θ))) → segCosCon2
  16. Segment((1, sin(Θ)), (1.5 + Θ / 2, sin(Θ))) → segSinCon
  17. Angle(cx, segRadius) → α