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高中数学第二册棱台中截面公式 2S_0~(1/2).=S~(1/2)+S′~(1/2)的证明,是一个很好的一题多证的例子。我在这一段教学中,给出多种证法,以培养学生灵活运用所学知识的能力。从多种证明中推衍出一个推广定理。证明如下:推广定理:平行于棱台底面的任意截面,若分棱台高成 m:n,则有
The proof of 2S_0~(1/2).=S~(1/2)+S’~(1/2) in the middle book of the second grade of the high school mathematics is a good example of multiple proofs. In this section of teaching, I gave a variety of evidence to help students develop their abilities to use their knowledge. Derive a promotion theorem from a variety of proofs. The proof is as follows: The promotion theorem: parallel to the arbitrary section of the bottom surface of the rib platform, if the dividing rib table is high to m:n, then there are