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solitaire_love
![](https://blog.hocmai.vn/wp-content/uploads/2017/07/hot.gif)
![](https://blog.hocmai.vn/wp-content/uploads/2017/07/hot.gif)
Đề
a ) 2cos2xcosx + cos2x = 3 – 4sin2 x
b ) 2sin2x – sinx = 2cos3x – cosx + cos2x
c ) Sin5x = 5sinx
a ) 2cos2xcosx + cos2x = 3 – 4sin2 x
b ) 2sin2x – sinx = 2cos3x – cosx + cos2x
c ) Sin5x = 5sinx