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Euclidean geomtry question

  1. Jul 20, 2010 #1
    proof the following using only euclidean geometry:
    Let S be any point inside a triangle ABC and let SP; SQ; SR be
    perpendicular to the sides BC;CA;AB respectively, then
    SA + SB + SC >= 2 (SP + SQ + SR)
    Hint: Set P1; P2 be the feet of the perpendiculars from R and Q upon
    BC. Prove fir st that (i) QR >= P1P2 and (ii) PRP1 and SBR are
    similar triangles.
  2. jcsd
  3. Aug 9, 2010 #2
    This is a standard inequality , named after Erdo:s.
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