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Centroid Line (Posted on 2010-08-10) Difficulty: 3 of 5


Let AA' and CC' be medians of ΔABC intersecting in point G. Let m be any line through G intersecting sides AB and AC.
Let P, Q, and R be the feet of perpendiculars to m from
A, B, and C respectively.

Prove that |AP| = |BQ| + |CR|.

  Submitted by Bractals    
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Solution: (Hide)
 
Let D be the foot of the perpendicular from A' to m.

Look at trapezoid BCRQ. A' is the midpoint of side BC.
Therefore, 2|A'D| = |BQ| + |CR|.

Look at similar triangles APG and A'DG. |AG| = 2|A'G|.

Therefore, |AP| = 2|A'D| = |BQ| + |CR|.

Comments: ( You must be logged in to post comments.)
  Subject Author Date
SolutionSolutionHarry2010-08-15 17:15:15
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