Pi Day Puzzle

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Across
  1. 4. Eastern European hand pie (lit: small pie in Russian)
  2. 7. Mountain range straddling the border of France and Spain. / Also dog breed: Great ______.
  3. 8. A line segment connecting two points on the circumference of a circle. / Also, group of notes played together, in music.
  4. 9. Director of 2012 movie “Life of Pi”
  5. 11. Famous Scientist born on Pi Day in 1879
  6. 13. πr² gives you the ____ of a circle
  7. 14. Distance around the circle
  8. 16. Iron disulfide (FeS2)
Down
  1. 1. Digit that does not appear in the first thirty decimals of Pi
  2. 2. Twice the radius
  3. 3. Famous US university that sends out admission letters on Pi Day (Acronym)
  4. 5. Pie that traditionally uses ground lamb
  5. 6. Pi is an _____ number
  6. 10. Number of digits in Pi
  7. 12. Person who appropriates or reproduces the work of another for profit without permission. Also, person who plunders a ship
  8. 15. The alphabet that the symbol for Pi is comes from