Sum of Interior Angles

The formula:

Sum of interior angles = (n - 2) x 180

1. Triangle (n = 3) (3 - 2) * 180 = 180 deg

2. Square (n = 4) (4 - 2) * 180 = 360 deg

3. Pentagon (n = 5) (5 - 2) * 180 = 540 deg

4. Hexagon (n = 6) (6 - 2) * 180 = 720 deg

5. Heptagon (n = 7) (7 - 2) * 180 = 900 deg

6. Octagon (n = 8) (8 - 2) * 180 = 1080 deg

7. Nonagon (n = 9) (9 - 2) * 180 = 1260 deg

8. Decagon (n = 10) (10 - 2) * 180 = 1440 deg

Summary: Sum of all Angles

Triangle: 180°

Square: 360°

Pentagon: 540°

Hexagon: 720°

Heptagon: 900°

Octagon: 1080°

Nonagon: 1260°

Decagon: 1440°