Trigonometric Ratios in Similar Right Triangles

Trigonometric Ratios in Similar Right Triangles
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2015-09-15 00:58
This GeoGebra example demonstrates trigonometric ratios (sine, cosine, tangent) in similar right triangles through dynamic geometry. Core mathematical concepts include: proportional corresponding sides in similar triangles, trigonometric identities for the same angle, and the functional relationship between angles and side lengths. Construction details: Polygon command creates multiple similar right triangles (poly1, poly2); Angle command marks angles (α, β); Point and Segment commands define key points and edges; Circle command constructs auxiliary circles; Rotate command performs rotations; Intersect command finds intersection points. This example is suitable for middle school mathematics (Grades 8-9) introductory trigonometry teaching, also useful for reviewing similar triangles and trigonometric ratio properties, helping students intuitively understand trigonometric ratio definitions and their invariance across different similar figures.

GeoGebra Commands & Parameters

  1. Intersect(xAxis, yAxis) → A
  2. Circle(A, 1) → c
  3. Intersect(c, xAxis, 2) → B
  4. Rotate(B, α, A) → B'
  5. Angle(B, A, B') → β
  6. Ray(A, B') → a
  7. Polygon(A, B', C) → poly1, c_1, a_1, b'
  8. Point(xAxis) → D
  9. Intersect(a, b) → E
  10. Polygon(A, E, D) → poly2, d, a_2, e
  11. Segment(A, D) → h
  12. Segment(A, E) → j