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利用三角形和多边形的内角及外角来计算较复杂图形中的角是数学竞赛中常见的题型之一,下面通过几个典型的例子来阐述解这类题目的基本思路和方法.例1如图1,∠CGE=α,则∠A+∠B+∠C+∠D+∠E+∠F=().(A)360°-α(B)270°-α(C)180°+α(D)2α(1999年山东省初中数学竞赛试题)图1解
Using triangles and polygonal inner and outer corners to calculate the angles in more complex graphics is one of the common types of questions in math contests. Here are some typical examples to illustrate the basic ideas and methods for solving such problems. Example 1 1, ∠CGE=α, then ∠A+∠B+∠C+∠D+∠E+∠F=().(A)360°-α(B)270°-α(C)180°+α(D)2α( 1999 Shandong Junior High School Mathematics Contest Questions) Figure 1 Solution