SSA Exploration – When Does the 'SSA Theorem' Hold?

SSA Exploration – When Does the 'SSA Theorem' Hold?
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2016-02-12 04:00
In collections Triangle Congruence
①This interactive GeoGebra example dynamically demonstrates the non-uniqueness of triangles given two sides and a non-included angle (SSA), and explores under what conditions the SSA configuration uniquely determines a triangle. ②Core mathematical concepts include the SSA ambiguity in triangle congruence, the sine rule, triangle existence conditions, multiple solutions, and similarity transformations. ③Construction highlights: using GeoGebra commands such as Point, Segment, Rotate, Angle, Ray, Circle, and Intersect, the applet builds segments a and b, angles α and β, points A, B, C, D, E, circles c and d, rays f and g, and text objects text1, text2, text3, with rotation and circle intersections revealing different possible triangles. ④Suitable for high school geometry or introductory college geometry, this exploration helps students understand the sufficiency of congruence criteria and fosters critical thinking through dynamic investigation.

GeoGebra Commands & Parameters

  1. Point(Circle[C, b_1]) → D
  2. Segment(C, D) → a
  3. Rotate(D, α, C) → D'
  4. Angle(D, C, D') → β
  5. Ray(C, D') → e
  6. Point(Circle[D, a_1]) → A
  7. Segment(D, A) → b
  8. Circle(D, A) → f
  9. Intersect(f, e) → B, E
  10. Segment(D, E) → c
  11. Segment(D, B) → d