In the Triangle

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Across
  1. 3. all its angles measure 60°
  2. 5. the symmetry axis of an angle
  3. 9. Pythagoras' favourite!
  4. 10. circle whose center is the intersection of two of definition*
  5. 11. their sum is always 180°
Down
  1. 1. connects the midpoint of a side and the opposite vertex
  2. 2. the symmetry axis of a side
  3. 4. 3 in a triangle
  4. 5. perpendicular to one side and through the opposite side
  5. 6. a triangle with only one symmetry axis
  6. 7. circle whose center is the intersection of two of the definition #
  7. 8. intersection of two of definition %