Crossword puzzle - I

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Across
  1. 2. FOUR
  2. 4. IDENTITY
  3. 7. HORIZONTAL
  4. 11. SECONDARY
  5. 12. AXIS
  6. 14. THREE
  7. 15. LINEAR
  8. 16. CO
  9. 17. DIHEDRAL
  10. 18. PERPENDICULAR
  11. 19. PYRAMIDAL
Down
  1. 1. NO
  2. 2. FALSE
  3. 3. PRINCIPAL
  4. 5. TETRAHEDRAL
  5. 6. PLANE
  6. 8. PLANAR
  7. 9. OCTAHEDRAL
  8. 10. CIRCLE
  9. 13. FIVE