Question 466766
here's a good reference that will help you understand convex and concave polygons.
<a href = "http://www.mathopenref.com/polygonconvex.html" target = "_blank">http://www.mathopenref.com/polygonconvex.html</a>
the convex polygon will not have an internal angle greater than 180 degrees.
the concave polygon will.
the figure shown in your jpg file looks very much like a concave polygon.
there is no such a thing as a regular concave polygon (see the reference).
your figure looks very much like a concave polygon.
from wikipedia:
A simple polygon that is not convex is called concave[2] or reentrant.[3] A concave polygon will always have an interior angle with a measure that is greater than 180 degrees.
It is always possible to cut a concave polygon into a set of convex polygons. A polynomial-time algorithm for finding a decomposition into as few convex polygons as possible is described by Chazelle & Dobkin (1985).[4]
end of from wikipedia: