Problem:
The circumference of the circle with center  is divided into  equal arcs, marked the letters  through  as seen below. What is the number of degrees in the sum of angles  and 
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Answer Choices:
A.  
B.  
C.  
D.  
E.  
Solution:
Angle is of or degrees, while is of or . Both triangles are isosceles, so the equal base angles are and respectively. The sum of angles and then is .
Answer: .
The problems on this page are the property of the MAA's American Mathematics Competitions