Tuesday, March 17, 2015

Geometry Problem 1100: Triangle, Circle, Centers, Vertex, Radius, Angle

Geometry Problem. Post your solution in the comment box below.
Level: Mathematics Education, High School, Honors Geometry, College.

Click the diagram below to enlarge it.

Online Math: Geometry Problem 1100: Triangle, Circle, Centers, Vertex, Radius, Angle.

2 comments:

  1. In ΔB₂C₂D,
    ∠B₂ = 90° - B/2
    ∠C₂ = 90° - C/2
    So ∠D = B/2 + C/2 = 90° - A/2

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  2. Let the incircle of ΔABC touch AB at X, AC at Y, and BC at Z.
    Note BX = BYand CY = CZ.
    Follows B1B2 // XY and C1C2 // YZ.
    Hence ∠B2DC2 = ∠ZYX = 90° - A/2

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