

Cho x1 = 6cos(wt+pi/3)cm , x2 = 2Căn3cos(wt-pi/2)cm và x = x1 + x2 thì
A. x = 2Căn3cos(wt-pi/6)cm . B. x = 2Căn3cos(wt+pi/6)cm .
C. x = 2cos(wt-pi/6)cm . D. x = 2cos(wt+pi/6)cm .
A. x = 2Căn3cos(wt-pi/6)cm . B. x = 2Căn3cos(wt+pi/6)cm .
C. x = 2cos(wt-pi/6)cm . D. x = 2cos(wt+pi/6)cm .