Sinusoidal steady-State proplem

[tinhnho]

hi everyone

I have a hard time to figure out these proplems in the picture.

Here are my solutions:

1) V1 = V*R/(R+ L) (voltage divider)
but we have V = cos(wt)
=> V1 = cos(wt)*R/(R+L)

2) L* di/dt + R*I = V1*cos( w*t + http://courses.ece.uiuc.edu/ece329/text/Image795.gif )
==> V1 = (L*di/dt + R*I)/cos(w*t +http://courses.ece.uiuc.edu/ece329/text/Image795.gif)

3) ?

4) V2 = R/(R +C)

5)?

6)?

7) ?

For the picture click here (http://viethost4u.com/toan/circuit due NOV-8.gif)

Thanks for reading