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Challenging geometry problem: congruent triangles
 

  1. AD is an altitude of triangle ABC. Points E, F and G are midpoints of the sides AB, BC and CA, respectively.
    Prove that ∆DEG is congruent to ∆FGE


     

  2. In ∆ABC, D is the midpoint of side AB. Extend BC to E so that CE = ½ BC. Draw DE, intersecting AC at F.
    Prove that DF = FE


     

  3. In ∆ABC with ∠ACB = 90°, CD is the altitude to hypotenuse AB. CM is the median to hypotenuse AB. CE is the bisector of ∠ACB.
    Prove that CE is the bisector of ∠DCM.


     

  4. BD and CE are altitudes to sides AC and AB of ∆ABC, respectively. F is the midpoint of BC, and G is the midpoint of DE.
    Prove that FG DE.


     

  5. In ∆ABC, BD and CE are bisectors of ∠ABC and ∠ACB. Perpendiculars drawn from A to BD and CE meet BD and CE at G and F respectively.
    Prove that FG || BC.