electric circuit, AC, 幫幫我!

(a) w = 5000rad/s
Xc = -j / (5000*2.5e-6) = -j80 ohm
XL = j(5000)(48e-3) = j240 ohm
Converting the ig to the polar form, ig = 200<0 mA
Let current flow through to the 240ohm and 2.5uF capacitor path as I1.
I1 = 200( (80+j240) / (80+240+j240-j80) ) = 141.42<45 mA
Vo = (141.42<45)(240)/1000 = 33.94<45V
Changning the Vo to rectangular form, Vo = 33.94cos(5000t + 45)V

(b) If the angular frequency is changed to a large value, XL = infinitive and XC = approximated to zero. Therefore, no current flow through to the 80ohm resistor and 48mH inductor's path. All of current flows to the other path.
Vo = (240)(200/1000) = 48V