area
the perimeter. the space inside is the area
It is its square area
A perpendicular segment drawn from a vertex to the line that contains the opposite side
A polygon region is the area inside the boundaries of a polygon.
No it is not. A polygon is a plane space enclosed by straight lines. A letter "E" does not enclose any space and so cannot be a polygon.
Then the point is not outside the polygon...?
It is the interior of the polygon.
are you asking for the angle measure of an angle inside a polygon? Not sure what you want to know.
the circle is inscribed in the polygon
It is concave.
Convex
A polygon is convex if you can take any two points inside the polygon and connect them with a line segment that is completely contained by the polygon. A non-convex polygon is one which contains at least two points such that the line joining them does not lie entirely inside the polygon.