24.2与圆有关的位置关系(国外英语资料).docVIP

24.2与圆有关的位置关系(国外英语资料) The positional relation of a circle Guidance of learning Including point and position, the circle line and position relationship, round round and round and round about the position location. These position relations have a common characteristic, namely each position has the corresponding quantitative characteristics, or that each position corresponds to a a number of relationships. This interweaving position and quantity constitute the main theme of this section study. At the same time, further research on each position relations, will come out of some important conclusions. Therefore, to summarize, the scattered knowledge assembled into a complete knowledge system, we study the festival is also a must face. Thinking integration Analytic emphasis 1., after three points of the circle A circle without three points on the same line is no doubt that not in the same line is the premise of the conclusion In addition, we must clear two characteristics: (1) the excenter triangle center is the intersection of three sides of a triangle perpendicular bisector; (2) out to a distance equal to the three vertices of the triangle. [example 1] as shown in Figure 24 - 2 - 1 is a broken wheel plate, try to determine its center of the circle Analysis to determine the center of the circle, only three different points in the residual broken wheel piece of arc, this time round the center is actually the three points of the triangle of the Circumcenter (the three point is not in the same line), and the Circumcenter is three sides of a triangle perpendicular bisector intersection point. Solution: 1. take three points A, B, C. on the known arc 2. connect AB, BC. 3., the vertical bisector MN and PQ of line segment AB and BC intersect at point O. respectively Then the O point is the center of the circle I used three points not in the same line of this conclusion is a circle, can determine the unknown center circle (ARC) in the center. The judgement and property of 2. tang