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Mathematics Dictionary
Dr. K. G. Shih

Senior High Mathematics
Question Q003



Q002 Ex-central triangle

Outlines
  • Q01 | What is ex-central triangle ?
  • Q02 | Properties of ex-central triangle
  • Q03 | Pedal triangle
  • Q04 | Diagram : Ex-central triangle
  • Q05 | Diagram : Pedal triangle
  • Q06 | Five centers of triangle ANC
  • Q07 | Reference


1. What is Ex-central triangle

Construction
  • 1. Draw a triangle ABC ?
  • 2. Draw three es-centers J, K, L of triangle ABC
  • 3. Join the centers J, K, L as vertices of the triangle JKL
  • 4. Triangle JKL is called ex-central triangle

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2. Properties of ex-central triangle

Properties
  • 1. Prove that J, C, K are colinear
  • 2. Prove that I is the in-center of triangle ABC
  • 3. Prove that I is also the orthocenter of triangle JKL
  • 4. Prove that ABC is pedal triangle of triangle JKL
  • 5. Prove that the tangent length is s from A to ex-circle
Note
  • The proof can be found in reference

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3. Pedal triangle

  • Prove that ABC is pedal triangle of triangle JKL
Note
  • The proof can be found in the reference

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4. Diagram : Ex-central triangle


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5. Diagram : Pedal triangle


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6. Five centers of triangle ABC

  • Study subjects : The five centers of triangle
    • Centroid
    • Circum-center
    • Ex-center
    • In-center
    • Ortho-center


    Go to Begin

    7. Reference

  • Study subjects : The ex-central triangle.
    • Prove that J, C, K are colinear.
    • Prove that I is the in-center of triangle ABC.
    • Prove that I is also the orthocenter of triangle JKL.
    • Prove that ABC is pedal triangle of triangle JKL.
  • Study subjects : The ex-central triangle
    • GE 18 03 | - Ex-center : Concurrent of bisectors of triangle
    • GE 18 04 | - In-center of triangle ABC is ortho-center of triangle JKL
    • GE 18 05 | - The tangent from A to ex-circle is s


    Go to Begin

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