1. Prove that 2tanA/(1+tan²A) = sin2A
2. Prove that sin3A/sinA + cos3A/cosA =4cos2A
3. Prove that 2sinA/(tan2A-tanA) = cosA+cos3A
4. Prove that 4cosAcos3Acos5A = cosA+cos3A+cos7A+cos9A
Maths M2
2015-03-01 8:20 am
回答 (1)
2015-03-01 10:10 am
✔ 最佳答案
Please Read：圖片參考：https://s.yimg.com/rk/HA07344914/o/1907831292.png
2015-03-01 13:35:28 補充：
Sorry
第2題尾3哥行 分子打少左個2
It should be
=2 ( 2 sin 2A cos 2A ) / sin 2A
=4 cos 2A
∴ sin 3A / sin A + cos 3A / cos A = 4 cos 2A
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http://postimg.org/image/97y8gblyl/
收錄日期: 2021-04-15 18:24:35
原文連結 [永久失效]:
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