understanding shapes (including polygons)

12345678
Across
  1. 2. closed curve) what is closed curve called when it does not pass through any point of it more than once?(simple closed curve)
  2. 4. curve) what is the name of a curve which does not cut itself called?(open curve
  3. 6. what is the intrior of a curve together with its boundary called?(region)
  4. 7. 180 * is the sum of angles in what shape?(triangles)
  5. 8. how many side does a octagon have? number name (eight)
Down
  1. 1. a polygon is said to be a regular polygon if its interior angles are ________?(equal)
  2. 2. how many types of polygons are there?(two)
  3. 3. ) what is the other name for concave polygons(reentrant )
  4. 4. "In mathematics, what is a straight line also called?"(curve)
  5. 5. curve) what do you call a curve which cuts itself?(open curve)
  6. 6. what is the number of possible diagonals that can go through a single vertex of a octagon to form many triangles as possible ? number name(six)