如图,在正方形ABCD的外侧,作等边三角形ADE,则∠AEB=( )
A:10°
B:15°
C:30°
D:150°
观察下列各式:
13=12
13+23=32
13+23+33=62
13+23+33+43=102
…
猜想13+23+33+…+103=____.