Geometry crossword

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Across
  1. 2. a statement to be proved
  2. 7. shape with six sides
  3. 8. 1d object
  4. 9. when the hypothesis and conclusion are wrong
  5. 11. assuming something is right
  6. 12. shape with eight sides
  7. 13. line or line segment dividing an angle into 2 equal parts
  8. 15. an angle measuring less than 90 degrees
  9. 16. shape with four sides
  10. 18. 2d object going both ways infinitely
Down
  1. 1. an angle measuring more than 90 degrees
  2. 3. center of a shape
  3. 4. triangle with all sides having different lengths
  4. 5. d = \sqrt{(x_2 - x_1)^2 + (y_2-y_1)^2}
  5. 6. A2+B2=C2
  6. 10. an angle measuring 90 degrees
  7. 14. center of a line segment
  8. 17. a half infinite line