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Across
  1. 5. The total length of the boundary of a closed figure
  2. 6. A polygon with three sides.
  3. 7. The amount of surface enclosed within a boundary.
Down
  1. 1. The longest side of a right-angled triangle.
  2. 2. A triangle with all three sides of different lengths.
  3. 3. A triangle with two equal sides.
  4. 4. A triangle with all sides equal.