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103桃園高中

想問計算1(2)這樣做錯在哪裡呢?
\(\displaystyle \frac{1}{\overline{AF_1}}+\frac{1}{\overline{BF_1}}=\frac{4}{\frac{2b^2}{a}}=\frac{2a}{b^2}\)
\(\displaystyle \overline{AF_1}+\overline{BF_1}=2at\)
\(\displaystyle \overline{AF_1}\times \overline{BF_1}=b^2t\)
\(\Delta ABF_2=\sqrt{S\times \overline{AF_1}\times \overline{BF_2}
(S-\overline{AF_1}-\overline{BF_2})}=\sqrt{2ab^2t(2a-2at)}\)
\(=\sqrt{-4a^2b^2t^2+4a^2b^2t}\)
\(=\sqrt{-4a^2b^2(t-\frac{1}{2})^2+a^2b^2}\)

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回復 61# thepiano 的帖子

太好了,謝謝鋼琴老師!

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