Boundaries of the polygon may extend to infinity . 多角形的边界可以延伸到无穷远处。
2.
At the same time convert the angle of the polygon at that vertex into a straight angle . 同时把该顶点处多角形的角转换成平角。
3.
1 . 1 observation of culture cells with phase contrast microscope the smg cells cultured are polygon epithelium cells and could go down to 3 to 4generations and live up to 3 - 4w in the medium ( dme 1 .相差倒置显微镜下观察smg细胞生长期间呈扁平状，单层生长，为多角形的上皮细胞，细胞可传代生长3一4代，存活3一4w 。
