POLICE

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Across
  1. 2. a angle equal to half the angle from one end of a line segment to the other
  2. 4. n-sided polygon in which the sides are all the same length and are symmetrically placed about a common center
  3. 5. A simple polygon, if at least one of its internal angles is greater than 180 degrees
  4. 7. a triangle with all three sides of equal length
  5. 10. an angle greater then 90°
  6. 11. A triangle with an angle of 90 degrees
Down
  1. 1. Lines that lie in the same plane, and are the same distance apart over their entire length
  2. 3. the slope of one is the negative reciprocal of the other
  3. 6. are the angles opposite each other when two lines cross
  4. 8. A triangle where all three internal angles are acute (less than 90 degrees)
  5. 9. a triangle with (at least) two equal sides