在解决直线形问题时,适当添加辅助圆,为圆的丰富性质的使用创造条件,常能使问题获得简解或巧解.下面举例加以说明.一、过共端点的等长线段的另一端点作圆当已知条件中存在共端点的等长线段时,以公共端点为圆心,等长线段为半径作圆,可以沟通圆心角、圆周角、弦、弧等的联系,使问 In solving linear problems, the appropriate addition of auxiliary circle, the rich nature of the use of the circle to create conditions that often make the problem can be simplified or clever solution .Examples to illustrate.At the same time, over the co-end of the length of the other end When the dot is a circle, when the isoline segments with the same endpoint exist in the known conditions, the circle with the common endpoint as the center and the segment with the same length as the radius can be used to communicate the central angle, the circumferential angle, the chord, the arc and so on