Pi Day!

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Across
  1. 3. the number of radians in a full circle
  2. 6. distance around a circle
  3. 7. a circle measured using angles based on π instead of degrees uses this unit
Down
  1. 1. a many-sided shape used historically to approximate circles
  2. 2. distance across a circle through the center
  3. 4. distance from the center of a circle to its edge
  4. 5. the branch of math that studies shapes and space