Question

The measure of an exterior angle at the vertex of a polygon equals the measure of the adjacent interior angle.

Always, sometimes, or never

Answer 1

so an exterior angle at the vertex of a polygon not can being never equal the measure of the adjacent interior angle 

Answer 2

Polygon: A polygon is a simple closed curve entirely made up of line segments.

1. As starting from triangle

Three kind of triangles: Isosceles, Scalene , and equilateral triangle

In none of these measure of an exterior angle at the vertex of the triangle equals the measure of the adjacent interior angle.

2. Quadrilateral = Parallelogram, Rhombus, Rectangle, Square, Kite, Trpzm

Apart from Rectangle and Square none other quadrilateral have The measure of an exterior angle at the vertex of the quadrilateral equals the measure of the adjacent interior angle.

we can also consider other polygons also like pentagon,hexagon,heptagon.

Decagon and found that it is not always possible that measure of an exterior angle at the vertex of a polygon equals the measure of the adjacent interior angle.

So, the correct option is Sometimes.