geometry

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Across
  1. 2. polygon with 3 sides.
  2. 4. triangle with 2 equal sides.
  3. 6. the co-interior and co-exterior angles
Down
  1. 1. a line that intersects 2 or more lines at 2 or more distinct points
  2. 3. the angles with common vertex and common arm
  3. 5. one of the angle is greater than 90 degree.