Parallel connection between capacitors

[-marko-]

I don't know how to start solving attached problem (3.126 from Irodov) because I can't identify any series or parallel connection between capacitors. I came to an idea that I should "break" capacitor C3 into two capacitors and then get two series and one parallel connections.

Any ideas?

 

[Meir Achuz]

That looks like it needs a "delta-->Y transformation".
It is more commonly used for resistors, but also works for capacitors

 

[berkeman]

The circuit is real and solvable, it just is not conducive to using the usual parallel & series simplification equations.

Try it this way. First solve the simplified version where the components are resistors. Ground the Vb end, and solve for the two middle node voltages as a function of the drive voltage Va. That gives you the inside currents, and that gives you the overall impedance since you know the drive voltage Va. Now just change the components back to capacitors and solve the same equations with the capacitive impedances.