Write a rule to find the sum of interior angles for any polygon:

Exercise: Using the rule above, find the sum of interior angles of the given polygon

1. A quadrilateral

2

A pentagon

3. An octagon

4. A polygon with 11 sides

5. A polygon with 15 sides

quadrilateral: (4-2) * 180=360

pentagon： (5-2) * 180=540

octagon: 6*180=540

11 sides: 9*180=1620

15 sides; 13*180=2340

Step-by-step explanation:

a n sides convex polygon has Sum of interior angle

S = (n - 2) * 180°

quadrilateral: (4-2) * 180=360

pentagon： (5-2) * 180=540

octagon: 6*180=540

11 sides: 9*180=1620

15 sides; 13*180=2340