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现行九年义务教育三年制初级中学《几何》第二册第 1 1 2页复习题三A组有这样一道习题 :题 已知 △ABC的∠B和∠C的平分线BD、CE相交于点I。求证 ∠BIC =π2 +12 ∠A。本文先给出该习题的解答 ,然后再在该习题的基础上做一些有趣的变形。分析 本道题中∠BIC为三角形两条内
The current nine-year compulsory education for a three-year junior secondary school “Geometry” Volume II, page 141 of Review Questions Three Group A has such an exercise: the title of known △ ABC ∠B and ∠C bisector BD, CE intersect at Point I. Prove that ∠BIC =π2 +12 ∠A. This article first gives the answer to this exercise, and then make some interesting changes based on the exercise. Analysis of this question in the BIC is triangle within two