What is the outside angle of a convex polygon?

I’ll try to explain in my own words. We know what a convex polygon is – it is a figure, all points of which, relative to any of its straight lines, lie in one half-plane (i.e., on one side). The internal angle is the angle at any of its vertices, which is inside the polygon, in itself.
Therefore, the outer corner is the corner adjacent to the inner one. Moreover, relative to one inner corner, i.e. one vertex, external corners can be two, and they are necessarily equal (as vertical).