JAMB Mathematics 2017 Paper

Concept:In a regular polygon, each interior angle and its corresponding exterior angle add up to $180^\circ$.Explanation:Let the exterior angle be $x$.The interior angle is twice the exterior angle, so interior angle $= 2x$.Since they are supplementary, $2x + x = 180^\circ$.Therefore, $3x = 180^\circ$, giving $x = 60^\circ$.So the exterior angle is $60^\circ$.For a regular polygon, the sum of all exterior angles is $360^\circ$.Thus, $60^\circ \times n = 360^\circ$, where $n$ is the number of sides.So $n = \frac{360}{60} = 6$.Answer:The polygon has $6$ sides. The correct option is B.