Verified answer

Number of Triangles

1. Triangle

• 3

2. Quadrilateral

• 4

3. Pentagon

• 5

4. Hexagon

• 6

5. Heptagon

• 7

6. Octagon

• 8

7. Nonagon

• 9

8. Decagon

• 10

9. Undecagon

• 11

10. Dodecagon

• 12

If the inner angle is less than 180°, it is a cx; if not, it is a cv.