Across
- 2. Intersection of two of definition 7
- 4. Has a center of symmetry
- 6. Two opposite parallel sides
- 7. Their sum is always 180°
- 9. A circle whose center is the intersection of two of definition 12
- 12. The symmetry axis of an angle
- 13. A triangle with only one symmetry axis
- 16. Connects the midpoint of a side and the opposite vertex
- 19. Two diagonals lie outside!
- 20. The most perfect quadrilateral
- 21. 4 equal sides
Down
- 1. A concave kite
- 3. Pythagoras' favourite triangle!
- 5. 4 right angles
- 7. Perpendicular to one side and through the opposite vertex
- 8. All its angles measure 60°
- 10. A circle whose center is the intersection of two of the definition 11
- 11. The symmetry axis of a side
- 14. Three in a triangle
- 15. One diagonal is a symmetry axis
- 17. One diagonal lies outside
- 18. Nothing special!