definitions and abbreviation puzzle

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Across
  1. 2. lines that have exactly one point in common
  2. 4. A polygon with congruent sides and angles
  3. 7. a parallelogram with four right angles
  4. 12. An angle that measures 180 degree
  5. 13. a quadrilateral with two pairs of parallel lines
  6. 16. a quadrilateral with exactly one pair of parallel sides
  7. 18. a triangle with all Angeles less than 90 degree
  8. 19. on an angle or polygon
  9. 20. a segment that has both end points on the circle
Down
  1. 1. set of points in a plane and all the same distance from given point
  2. 3. a triangle with at least two congruent sides
  3. 5. lines that intersect to form right angles
  4. 6. closed plane figure formed by 3 or more lines
  5. 8. 2 angles whose measures add to 90 degree
  6. 9. an angle that measures less than 90 degree
  7. 10. a figure formed by two rays with a common endpoint
  8. 11. a flat surface that extends forever
  9. 12. a rectangle with four congruent sides
  10. 13. an exact location
  11. 14. part of a line that starts at one end point that goes forever
  12. 15. straight path that extends without end in opposite directions
  13. 17. a segment that passes through both end points of circle