analytic geometry

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Across
  1. 4. a segment that connects two midpoints of adjacent sides
  2. 6. a line that divide a segment in half
  3. 7. a triangle has three of those
  4. 8. slopes of ------- lines are the same
Down
  1. 1. a segment that connect a vertex with a middle of an opposite side
  2. 2. a line that is perpendicular to the given line segment
  3. 3. a middle of a line segment
  4. 5. product of ------ of perpendicular lines equals -1.