Geometry Puzzle

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Across
  1. 2. two pairs of adjacent congruent sides
  2. 3. four equal sides
  3. 9. if x=y, then y can be substituted in for x in any expression
  4. 10. two-dimensional closed figure made up of straight-line segments connected end-to-end
  5. 11. four equal sides and four right angles
  6. 13. an angle in a circle with its vertex on the circle
  7. 15. means to divide into two equal parts
  8. 17. an angle in a circle with its vertex on the circle
  9. 18. set of points a fixed distance from a center and is defined by a central angle
  10. 20. line that is perpendicular to the circle's radius
Down
  1. 1. formed by two radii of a central angle and the arc between their endpoints on the circle
  2. 4. a segment that connects the midpoints of any two sides of a triangle
  3. 5. Any two points on a circle. Usually referred to as the larger of two
  4. 6. a line segment that has both endpoints on a circle
  5. 7. a point that divides a line segment into two parts of equal length
  6. 8. both pairs of opposite sides are parallel
  7. 12. property if x=y and y=z then x=z
  8. 14. four right angles
  9. 16. property the measure of any side or angle is equal to itself
  10. 19. Any two points on a circle. Usually referred to as the smaller of two