Kasra's Puzzle

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Across
  1. 4. A kind of triangle with all angles smaller than 90 degrees
  2. 6. A shape with ten sides
  3. 8. A type of triangle with no equal sides
  4. 9. a quadrilateral shape with one pair of parallel sides
Down
  1. 1. the distance around a circle
  2. 2. the size of a shape
  3. 3. A shape with multiple sides
  4. 5. A quadrilateral shape with 2 pairs of parallel side
  5. 7. to cover a surface with tiles that have no spaces or overlap