Problem: In the adjoining figure, ABCD is a square, ABE is an equilateral triangle and point E is outside square ABCD. What is the measure of β AED in degrees?
Answer Choices:
A. 10
B. 12.5
C. 15
D. 20
E. 25
Solution:
Since β DAE=90β+60β=150β and DA=AB=AE,β AED=(2180β150β)β=15β.