Pi day puzzle

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Across
  1. 1. / the shape that pi is associated with
  2. 3. / pi is related to this form of measurement
  3. 4. / 22/7 represent pi in _________ form
  4. 5. / amount of digits in pi
  5. 7. / 2pi = 360 __________
Down
  1. 2. / pi relates diameter and _________
  2. 6. / pi is a letter in the _________ alphabet