CB´s math puzzle

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Across
  1. 3. to put something in a group or identify
  2. 7. completely equal to another shape
  3. 8. two rays with an end point
  4. 9. when to faces meet on at 3D shape
Down
  1. 1. the measurement of the distance around the shape
  2. 2. a 8 sided polygon
  3. 4. a line segment the makes a boundary on a 2D shape
  4. 5. a flat surface on a shape
  5. 6. a polygon with 5 side
  6. 8. angle a angle that less than 90 degrees.