super sigma Silas puzzle

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Across
  1. 4. a shape that has equal angles
  2. 7. Divide a shape in two equal parts.
  3. 8. an intersection where both lines form four 90° angles
  4. 10. a triangle with two sides of an equal length
  5. 11. more than two shapes that have the same exact dimensions
  6. 13. a quadrilateral that has been stretched out
  7. 14. a shape with four sides and four 90° angles
  8. 17. a figure on a plane with at least three sides that connects and form 360° exterior
  9. 18. a Line that connects the midpoints of a trapezoid or triangle
Down
  1. 1. a shape which all sides have the same distance continuously between them.
  2. 2. a quadrilateral which their diagonals form a lowercase t
  3. 3. a quadrilateral that consists of one parallel sides
  4. 5. a shape where all sides have the same dimensions
  5. 6. a shape where there are four sides
  6. 9. a regular rectangle
  7. 12. a shape where all sides are the same as well as angles
  8. 15. two angles that add up to be 180°
  9. 16. a line(s) that connects two vertices of a polygon