If the measure of exterior angle of a regular polygon is #1/5# times its interior angle, how many sides does the polygon has?

1 Answer
Apr 11, 2017

Polygon has #12# sides - it is dodecagon.

Explanation:

As the measure of the exterior angles of a regular polygon are #1/5# times the measure of its interior angles,

each exterior angle of the regular polygon too will be #1/5# times the measure of its interior angle.

Let the exterior angle be #x# and then interior angle would be #5x#

and as their sum is always #180^@#, we have

#x+5x=180^@# or #6x=180^@# i.e. #x=180/6=30^@#

Now as sum of exterior angles of a polygon is always #360^#

we have #(360^@)/(30^@)=12# exterior or interior angles i.e.

Polygon has #12# sides - it is dodecagon.