从上期“命题探源”栏目文章中我们知道,涉及的直角其顶点除了在梯形的顶点外,还有在腰上的情形,即顶点在直腰(腰与底垂直)上、顶点在斜腰(腰与底不垂直)上.它除了与圆结合命题外,还常常与二次函数结合构造命题.举例说明如下. From the previous issue of “proposition source” column we know that the vertices involved in its right addition to trapezoidal vertices, there are cases on the waist, that is, vertices in the straight waist (waist and bottom vertical), the vertices in the Oblique waist (the waist and the bottom is not vertical) .In addition to its combination with the circle proposition, it is often combined with the quadratic function proposition .For example as follows.