(28 points) In the drawing, a regular polygon is partially covered by a rectangle. what is the number of sides of this polygon?
A: 6
B: 7
C: 8
D :60
![28 points In the drawing a regular polygon is partially covered by a rectangle what is the number of sides of this polygonA 6B 7C 8D 60 class=](https://us-static.z-dn.net/files/d55/ffd53d5d2f5365ea8b609804302d4671.jpg)