geometry puzzle

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Across
  1. 3. Lines: Lines that cross each other at exactly one point.
  2. 7. The set of all points collinear to two points.
  3. 8. Lines: Two lines that intersect to form four right angles.
  4. 10. The middle point of a line segment.
  5. 12. Angle: An angle that measures greater than 90 degrees and less than 180 degrees.
  6. 15. The point in common of two rays that form an angle.
Down
  1. 1. The number of square units needed to cover a surface.
  2. 2. Angle: An angle whose measure is less than 90 degrees.
  3. 4. The distance around a figure.
  4. 5. Angle: An angle that forms a square corner and has a measure of 90 degrees.
  5. 6. A flat figure with no thickness that extends indefinitely in all directions.
  6. 9. A line with a single endpoint (or point of origin) that extends infinitely in one direction.
  7. 11. Lines: Lines in the same plane that never intersect and are always the same distance apart.
  8. 13. Angle: An angle whose measure is 180 degrees.
  9. 14. Two endpoints and all the points in between them.