triangles

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Across
  1. 2. if any two of its side are of the same length
  2. 4. an angle of 90°
  3. 6. if each one of its sides has the same length
Down
  1. 1. the perpendicular line segment from a vertex of a triangle to its opposite side
  2. 3. The line segment joining a vertex of a triangle to the mid point of its opposite side
  3. 5. a simple closed curve made of three line