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问题1有一只铅笔,其上某处有一个商标.若让铅笔的两端分别在两条互相垂直的直线上滑动,则该商标所形成的轨迹是什么图形?铅笔所形成的包络是什么图形?如图2,以两条互相垂直的直线为坐标轴,建立平面直角坐标系.设铅笔长为l,商标所对
Question 1 has a pencil with a mark somewhere on it, what is the trace of the mark formed by the two ends of the pencil sliding on two mutually perpendicular lines, and what is the envelope formed by the pencil Figure 2, with two straight lines perpendicular to each other as the axis, the establishment of rectangular Cartesian coordinate system set pencil length l, the trademark of the