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JAMB Mathematics 2019 Paper

Question : 46

Total: 73

Solution:

Concept:

For a regular polygon, each interior angle is supplementary to its exterior angle, and the exterior angles always sum to

360^\circ

Explanation:

Each interior angle is

140^\circ

Therefore, each exterior angle is

180^\circ - 140^\circ = 40^\circ

The number of sides

n

of the polygon is:

n = \frac{360^\circ}{40^\circ} = 9.

The sum of all interior angles is:

\text{Sum} = 140^\circ \times 9 = 1260^\circ.

Answer:

The sum of all the interior angles of the polygon is

1260^\circ

Correct option: B.

1260^\circ

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