Question:
Tick (✓) the correct answer:
In a regular polygon, each interior angle is thrice the exterior angle. The number os sides of the polygon is
(a) 6
(b) 8
(c) 10
(d) 12
Solution:
(b) 8
For a regular polygon with $\mathrm{n}$ sides:
Each exterior angle $=\frac{360}{n}$
Each interior angle $=180-\frac{360}{n}$
$\therefore 180-\frac{360}{n}=3\left(\frac{360}{n}\right)$
$\Rightarrow 180=4\left(\frac{360}{n}\right)$
$\Rightarrow n=\frac{4 \times 360}{180}=8$