Calculate the number of sides of a regular polygon if:

(i) its interior angle is five times its exterior angle.

(ii) the ratio between its exterior angle and interior angle is 2 : 7.

(iii) its exterior angle exceeds its interior angle by 60°.

Each interior angle of a regular polygon is 165°. The number of sides in the polygon is :

1. 12

2. 24

3. 20

4. 6

A polygon has n sides, the number of diagonals in this polygon is:

1. $\dfrac{1}{2}n(n - 1)$

2. $\dfrac{1}{2} \times n(n - 2)$

3. $\dfrac{1}{2} \times n(n - 3)$

4. $\dfrac{1}{2} \times n(n - 4)$

The interior angle of a regular polygon is four times its exterior angle. The number of sides in the polygon is:

1. 12

2. 10

3. 15

4. 18