Question

What is the measure of an exterior angle of a regular
decagon?

Answer 1

the exterior angles of any polygon sum to 360 degrees.... just a geometry fact you need to know.

so if the polygon is regular, all angles are equal in their measures, including the exterior angles.

so just divide 360 by the number of angles or sides in the polygon to get the measure of 1 exterior angle.

Answer 2

thank you :D