Ans: C
Note that the sum of all exterior angles of a regular $n$-sided polygon and the interior angle of the polygon are $360^\circ$ and $\dfrac{(n-2)\times180^\circ}{n}$ respectively. Hence, we have
Note that the sum of all exterior angles of a regular $n$-sided polygon and the interior angle of the polygon are $360^\circ$ and $\dfrac{(n-2)\times180^\circ}{n}$ respectively. Hence, we have
$\begin{array}{rcl}
3 \times \dfrac{(n-2)\times180^\circ}{n} & = & 360^\circ \\
\dfrac{n-2}{n} & = & \dfrac{2}{3} \\
3(n-2) & = & 2n \\
3n – 6 & = & 2n \\
n & = & 6
\end{array}$
