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问题: 高一数学。很简单的。

化简(4-5cosα)/(3-5sinα)+(3+5sinα)/(4+5cosα).

解答:

(4-5cosα)/(3-5sinα)+(3+5sinα)/(4+5cosα).
=[(4-5cosα)(4+5cosα)+(3+5sinα)(3-5sinα)]/(3-5cosα)(4+5sinα)
=[16-25(cosα)^+9-25(sinα)^]/(3-5cosα)(4+5sinα)
={25-25[(cosα)^+(sinα)^]}/(3-5cosα)(4+5sinα)
=(25-25)/(3-5cosα)(4+5sinα)
=0