A.i1超前i260° B.i1滯后i260° C.相位差無法判斷
A.u(t)=20cos(314t+40°)V B.u(t)=20cos(50t+40°)V C.u(t)=28.28cos(50t+40°)V D.u(t)=28.28cos(314t+40°)V
A.4cos314t B.6sin(5t+17°) C.4cos2πt