Find the measures of an interior angle and an exterior angle of a regular polygon with 6 sides.

The sum of the external angles of a polygon is always 360°

To find the measure of one angle, the formula is 360/n where n is the number of the sides of the polygon.

360/6 = 60°

The sum of all internal angles of a polygon can be find with the formula (n-2) * 180° where n is the number of the sides. In this case 180 (6-2) = 180*4 = 720°

To find one internal angle, follow this formula [180 (n-2) ] / n = [720/6] = 120°

Anyway, you can pick a vertex and from that vertex start to draw diagonals.

There will be some triangles, the sum of all internal angles of a triangle is 180°. In a polygon, the sum of all internal angles equals to the sum of all internal angles of all the triangles.

Hope I'm clear.