Felipe set his hinged mirror so that its angle was $36°$ and the core region was isosceles, as shown at right.  

1. How many sides did his resulting polygon have? Show how you know.

   Hint (a):

   How many times does $36°$ go into $360°$?

   Answer (a):

   Since $360°\div36°=10$, his regular polygon will have $10$ sides.

2. What is another name for this polygon?

   Hint (b):

   See the Math Notes box in Lesson 7.1.4 on regular polygons.