Three of the exterior angles of a hexagon are 40°, 51° and 86°. If each of the remaining exterior angles is x°, find the value of x.

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°.

Two angles of a quadrilateral are of 50° each and the other two angles are also equal. The measure of each of these equal angles is:

1. 130°

2. 310°

3. 155°

4. none of these

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