Question

The number of sides of the polygon in which all the interior angles sums to ${1980}^o$ is

• A. $11$
• B. $12$
• C. $13$
• D. $14$

Answer 1

The correct option is C $13$

Let the number of sides of polygon be $n$

We know,
Sum of all interior angles=${180}^o(n-2)$
${1980}^o={180}^o(n-2)$
$n-2=\frac{{1980}^o}{{180}^o}$
$n-2=11$
$n=11+2$
$n=13$

Hence the number of sides of polygon whose all interior angles sums to ${1980}^o$ is $13$. Option $\left(c\right)$ correct.