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由于特殊问题的解决孕育着一般问题的解决,因此,将一般问题特殊化是探索解题途径常见的思想和方法,它在解题中有着不可小视的作用。 一、特殊化的直接功能 在解题时,有许多问题利用特殊化思想直接解决效果甚佳,特别是对某些选择题或填空题,因为只要求结果,直接赋以特殊数值或取特殊位置,答案便垂手可得。 例1 如图1,∠A、∠B、∠C、∠D、∠E和∠F的度数之和是90°×n,其中n等于( )。 A.2 B.3 C.4 D.5 E.6(1985年镇江市初中数学竞赛题) 解:将图1画成图2的特殊情形,即得n为4.故选C.
Because the solution of special problems gestates the solution of general problems, the specialization of general problems is a common way of thinking and method for exploring solutions to problems. It has a very important role in solving problems. First, the direct function of specialization When solving a problem, there are many problems using specialization ideas to directly solve the effect is very good, especially for some multiple choice or fill in the blank, because only the results are required, directly assigned a special value or take a special position The answer is within your reach. Example 1 As shown in Fig. 1, the sum of the degrees of ∠A, ∠B, ∠C, ∠D, ∠E, and ∠F is 90°×n, where n is equal to (). A.2 B.3 C.4 D.5 E.6 (The Zhenjiang Junior High School Mathematics Competition in 1985) Solution: The special case of Fig. 1 is drawn as Fig. 2, that is, n is 4. Therefore, C.