Question

If the sum of the interior angles of a polygon is ${1440}^{\circ }$, then it has ___ sides.

• A. 10
• B. 12
• C. 16
• D. 20

Answer 1

The correct option is A

10

Let the polygon have 'n' sides.
Sum of interior angles $=(n-2)\times {180}^{\circ }$

${1440}^{\circ }=(n-2)\times {180}^{\circ }$

$n-2=\frac{{1440}^{\circ }}{{180}^{\circ }}$

$n-2=8$
$n=10$