Mathematics crossword!

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Across
  1. 5. Two lines that touch with a 90 degrees angle
  2. 7. Exterior size of a circle
  3. 8. A right ….. has 90 degrees
  4. 10. Figure with multiple sides
  5. 11. Round figure
  6. 12. Polygon with four equal sides
Down
  1. 1. Quadrilateral figure with four right angles
  2. 2. Interior size of a circle
  3. 3. Figure with 4 sides
  4. 4. My friend sits by my.....
  5. 5. Two lines that don't touch
  6. 6. Part of a line
  7. 9. The diameter of a circle is equal to 2x its.....