got to do the cooking by the book, you know you cant be lazy!

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Across
  1. 5. 2 lines that intersect or meet
  2. 9. total length of it's boundary
  3. 11. all the squares inside of a shape
  4. 12. 90 degrees
  5. 13. Triangle A= b x h
  6. 14. amount of space in 3D object
  7. 15. 3D shape opened out and laid flat.
Down
  1. 1. a triangle that has 3 unequal sides
  2. 2. a solid 3D object
  3. 3. a 2D shape
  4. 4. Where 2 points meet
  5. 6. 3 triangles come together to be 3D
  6. 7. The area of the surface on a 3D shape
  7. 8. If all the sides are equal
  8. 10. Making shapes equal