What are the mathematical names of the first ten polygons and their properties?

Answer 1

All polygons have 3 or more sides having exterior angles that add up to 360 degrees and the first 10 can be classed as follows in order of their geometrical names, number of sides, sum of interior angles and number of diagonals:-

1 Triangle: 3 sides, 180 degrees and no diagonals

2 Quadrilateral: 4 sides, 360 degrees and 2 diagonals

3 Pentagon: 5 sides, 540 degrees and 5 diagonals

4 Hexagon: 6 sides, 720 degrees and 9 diagonals

5 Heptagon or Septagon: 7 sides, 900 degrees and 14 diagonals

6 Octagon: 8 sides, 1080 degrees and 20 diagonals

7 Nonagon: 9 sides, 1260 degrees and 27 diagonals

8 Decagon: 10 sides, 1440 degrees and 35 diagonals

9 Undecagon: 11 sides, 1620 degrees and 44 diagonals

10 Dodecagon: 12 sides, 1800 degrees and 54 diagonals

Note that all polygons can be regular, irregular, congruent or similar