课本原题(人教版数学教材九年级上册第86页练习第1题)如图1,点A、B、C、D在同一个圆上,四边形ABCD的对角线把4个内角分成8个角,这些角中哪些是相等的角?图1是学习圆周角相关结论的一个重要的基本图形,结合本题的提问,熟悉其图形特征对今后的学习具有重要意义.本文从如下三个方面予以探究.1.基本结论探究图中标注的角有8个,比较多,如果凭感觉配对乱找,势必出错.观察图形,发现整个圆被A、B、C、D四点分成了四段弧,所标注的8个角均是它们所对的圆周角,而根据“在同圆或等圆中,同弧或等弧所 As shown in Figure 1, points A, B, C and D are on the same circle. The diagonal of the quadrilateral ABCD divides the four inner corners into eight Figure 1 is an important basic graph of the correlation conclusion of the study of the circumferential angle, with the question of this question, familiar with the graphic features of its future learning is of great significance.This article from the following three aspects To explore .1 basic conclusion of the figure in the figure marked angle of 8, more, if the feeling of matching and chaos to find, is bound to make mistakes.Observe the graphics and found that the entire circle is A, B, C, D four points into four Arc, the eight corners of the annotation are the right angle to them, and according to ”in the same circle or circle, the same arc or arc