為什麼2Sin^2 x+Cosx =2－2Cos^2 x+Cosx?

👨🏻‍🏫 學術台數學

[匿名]

2018-11-21 7:08 pm

回答 (1)

螞蟻雄兵

2018-11-21 7:33 pm

Sol
Sin^2 x+C0s^2 x=1
Sin^2 x=1-Cos^2 x
2Sin^2 x+COSx
=2(1-Cos^2 x)+Cosx
=2-2Cos^2 x+Cosx

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