圆既是轴对称图形,又是中心对称图形,还具有旋转不变性,在解决与圆有关的无图题时,由于受思维定式的影响,往往只考虑符合条件的常见的一种图形,从而造成漏解.常见的有涉及点和圆的位置关系、直线和圆的位置关系、圆和圆的位置关系、圆心和弦的位置关系、圆心和角的位置关系、和圆有关的动态问题等,解答这类问题时一定要全面考虑,分类并逐一加以讨论,这样才能避免漏解. The circle is both axisymmetric and centrosymmetric, and has the invariance of rotation. In solving the circle-related non-pictorial problem, the circle is usually considered only by the common one that meets the conditions, resulting in Commonly related to the location of the point and the circle, the relationship between the position of the line and the circle, the relationship between the location of the circle and the circle, the center of the relationship between the position of the chord, the center of the circle and the angular position, and the circular dynamic issues, etc. Such problems must be fully considered, classified and discussed one by one, so as to avoid leakage.