论文部分内容阅读
在学习相交线和平行线的内容时,经常会遇到一类根据所给已知条件不能直接得到答案的问题.这时需要我们学会识图,从所给图形中寻找条件,方可使问题得以顺利解决.一、从相交线中寻找条件1.找对顶角.例1如图1,AB上CD于点O,直线EF过点O,且∠AOE=40°,求∠DOF的度数.分析:由已知条件不能直接求出∠DOF的度数,但从图形中发现,∠AOE与∠BOF为对顶角,从而可求出∠DOF的度数.
When we study the content of intersecting lines and parallel lines, we often encounter a problem that we can not get the answer directly according to the given conditions, and we need to know the diagram and look for the conditions from the given figure before we can make the problem First, find the conditions from the intersection line 1. Find the right corner Example 1 As shown in Figure 1, AB on the CD at point O, the line EF over point O, and ∠ AOE = 40 °, find ∠ DOF degree Analysis: The degree of ∠DOF can not be calculated directly from the known conditions, but from the graph it is found that ∠AOE and ∠BOF are the vertex angles, so that the degree of ∠DOF can be obtained.