1 bài lương giác

2

2ku

Pt \Leftrightarrow cos5x - sin5x = cos2x -sin2x
Áp dụng CT cho cả 2 vế của PT: [TEX]cosx - sinx = \sqrt{2}cos(x+\frac{\pi}{4})[/TEX]
 
C

connguoivietnam

sin2x-cos2x=sin5x-cos5x
căn2.sin(2x-pi/4)=căn2.sin(5x-pi/4)
sin(2x-pi/4)=sin(5x-pi/4)
 
N

nguyenvankhanh_23793

- 2 cos 7x/2 sin 3x/2 = 2 sin 7x/2 sin 3x/2
2 sin 3x/2(cos 7x/2 + sin 7x/2)= 0
sin 3x/2=0 hoac cos 7x/2+sin 7x/2 = 0
 
You must log in or register to reply here.
Top Bottom