平面几何中的尺规作图限制只能用直尺和圆规,而这里所谓的直尺,是指没有刻度只能画直线的尺.用直尺与圆规当然可以作出许多种图形,但有些图形如正七边形、正九边形就作不出来.有些问题看起来好像很简单,但真正做起来却很困难.这些问题中最著名的就是古希腊人提出的三大几何问题. The limit ruler in plane geometry can only use rulers and compasses. The so-called ruler here refers to the ruler that can only draw straight lines without scales. Of course, many kinds of graphics can be made with rulers and compasses, but some graphics If the positive and the nine-sided shapes are impossible, some problems may seem simple, but it is very difficult to really do it. The most famous of these problems is the three major geometric issues raised by the ancient Greeks.