octagon

八边形，八角形英释中释na flat shape with eight sides and eight angles

1 Six identical triangles can be formed by drawing two straight lines through an octagon's center point..经过八角形的中心画两条直线，能够得到六个一样的三角形。

2 Why It's Innovative: A hydraulic system built into the bridge's handrail allows it to retract and curl into an octagon..创新点：这座桥的栏杆使用了液压驱动系统，使之能收缩卷曲成八边形。