Geometry puzzle (Emma)

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Across
  1. 4. segment joining the two base planes and perpendicular to both
  2. 6. is a prism where all sides are squares
  3. 7. all sides are the same
  4. 8. congruent polygons lying in parallel planes
  5. 10. where 2 rays meet
  6. 12. 2 angles added together equal 180 degrees
  7. 14. segment that connects two points on the circle
  8. 16. all angles are the same
  9. 17. Having a plane-like quality
  10. 18. A specific position on a line, plane, or in space
  11. 20. A closed figure with eight sides
Down
  1. 1. Identical in size and shape
  2. 2. Without a curve
  3. 3. the intersection point of two sides of a plane figure
  4. 5. Sides that are the same length
  5. 9. The meeting of two faces on a three-dimensional shape
  6. 11. Two lines that meet to make a corner
  7. 13. quadrilateral with both pairs of opposite sides parallel
  8. 15. directed line segment
  9. 19. has a vertex and a circular base