If you have a Lease, you should look to when the month-to-month obligations are effective. If it states that you pay on a calendar month basis, then your notice will be considered as being more that the required 30 days, and that you owe for the full following month.
A regular polygon is equiangular, which means all angles are the same measure. In the case of a regular hexagon, the sum of 720 degrees would be distributed evenly among the six sides. So, 720/6 = 120. There are six angles in a regular hexagon, each measuring 120 degrees.
We can then draw a right triangle using the vertex-to-vertex diameter of the hexagon as a hypotenuse. Since the diameter of such a hexagon is known to be 2, we are left with one undefined edge of our triangle, equal the distance between two opposing edges of the hexagon (which is twice the apothem).