两个正五边形的边长分别为m和n，这两个五边形（ ）（填相似或不相似）。
相似
They have great hamburgers ice cream. [ ]
A. and
B. or
C. so
D. too
If triangle AOB is equilateral, O is the center of the semicircle ABC, and the radius of semicircle ABC is 6, what is the length to BC
