N
noooo
con 4 con co the lam nhu sau
dat t=x+pi/3=>x+t-pi/3
thay vao phuong trinh ta co 8(cost)^3 +cos3t=0
den day dung cong thuc nhan 3 giai tip
dat t=x+pi/3=>x+t-pi/3
thay vao phuong trinh ta co 8(cost)^3 +cos3t=0
den day dung cong thuc nhan 3 giai tip