平行四边形

A prismatoid having polygons with the same number of sides as bases, and faces that are parallelograms or trapezoids.

四个相等的四形；不是直角的等四形。

In this chapter, we partially solve the problem of inner radius of univalence for some parallelogram, applying the properties of extremal sets of Schwarz derivatives.

在这一章中我们利用Schwarz 导数极值集的要质部分的解决了几类四形的单径。