cos2x + (1 + 2cosx)(sinx-cosx) = 0<=> (cos2x - sin2x) - (1 + 2cosx)(cosx - sinx) = 0<=> (cosx - sinx) (cosx + sinx - 1 - 2cosx) = 0* cosx - sinx = 0 <=> 1 - tanx = 0 (ĐK: cosx khác 0)<=> tanx = 1 <=> x = pi/4 + k.pi* sinx - 1 - cosx = 0 <=> (sinx - cosx)2 = 1<=> (sin2x - 2sinxcosx + cos2x) = 1<=> 2sinxcosx = 0<=> sinx = 0 <=> x = k.pi cosx = 0 <=> x = pi/2 + k.pi
cos2x + (1 + 2cosx)(sinx-cosx) = 0<=> (cos2x - sin2x) - (1 + 2cosx)(cosx - sinx) = 0<=> (cosx - sinx) (cosx + sinx - 1 - 2cosx) = 0* cosx - sinx = 0 <=> 1 - tanx = 0 (ĐK: cosx \neq 0)<=> tanx = 1 <=> x = \frac{\pi }{4} + k\pi* sinx - 1 - cosx = 0 <=> (sinx - cosx)2 = 1<=> (sin2x - 2sinxcosx + cos2x) = 1<=> 2sinxcosx = 0<=> sinx = 0 <=> x = k\pi cosx = 0 <=> x = \frac{\pi }{2} + k\pi
cos2x + (1 + 2cosx)(sinx-cosx) = 0<=> (cos2x - sin2x) - (1 + 2cosx)(cosx - sinx) = 0<=> (cosx - sinx) (cosx + sinx - 1 - 2cosx) = 0* cosx - sinx = 0 <=> 1 - tanx = 0 (ĐK: cosx
khác 0)<=> tanx = 1 <=> x = pi
/4 + k
.pi* sinx - 1 - cosx = 0 <=> (sinx - cosx)2 = 1<=> (sin2x - 2sinxcosx + cos2x) = 1<=> 2sinxcosx = 0<=> sinx = 0 <=> x = k
.pi cosx = 0 <=> x = pi
/2 + k
.pi