The Enveloping of Bi-parametric Surface Family and the Quadratic Enveloping of Singl-parametric Surface Family

This paper presents an approach to the enveloping of biparametric surf-ace family and the quadratic enveloping of single-parametric surface family. Both are expressed in terms of implicite or parametvic equations. A simple method fov solving the quadratic enveloping through solving of a bi-param-etric surface family and the equivalent enveloping conditions are established.