新知識出版社的“相似形”一書,其中第88頁關於相似法作圖題举了一例:“求作一个三角形的內接等腰直角三角形,並使其斜边平行於三角形的一边,其直角顶點在該边上。”書中關於討論部分是这样的:“(1)因为求作的內接等腰直角三角形之顶點,可在△ABC之任一边上,故本題恆有三解。(2)如当△ABC为銳角三角形或直角三角形恆可作圖。(3)如当△ABC为鈍角三角形,所求 The book “Similar Shapes” of the New Knowledge Publishing House, on page 88, shows an example of the similarity drawing problem: “To make a triangle inscribed in an isosceles right-angled triangle and to make its hypotenuse parallel to the side of the triangle, The vertices at the right angle are on this side.“ The discussion part of the book is this: ”(1) Since the vertices of the inscribed isosceles right triangles are inscribed on either side of ABC, there are three (2) If △ABC is an acute-angled triangle or a right-angled triangle, it can be plotted (3) If △ABC is an obtuse triangle,