Crossword piZone 2013

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Across
  1. 2. A plane shape bounded by a continuous line that is always the same distance from the center
  2. 5. The distance around a circle (perimeter) C = π d
  3. 7. The size of a surface a = π r2
  4. 8. Ratio of the circumference of a circle to its diameter π = C/d
  5. 9. Half the diameter of a circle r = d /2 r = C/2π
  6. 10. A three dimensional circle
  7. 12. The straight line passing from one side of the circle to the other
Down
  1. 1. A way to count part of something
  2. 3. The study of numbers, patterns, space, and change
  3. 4. A decimal number whose number goes on forever without repeating
  4. 5. Formed by taking 2 circles, putting one above the other, and wrapping a surface around to connect the edges
  5. 6. The amount of space inside of something like a sphere
  6. 11. The relation between two or more values
  7. 12. Like fractions because they count part of something