i have no idea for this . I found the max voltage of capacitor using voltage differences between two legs.

i can't find the time constant for charging the capacitor in second image .

 

You need to show YOUR best effort to solve YOUR homework problem. We won't do it for you.

HINT: Consider the Thevenin equivalent circuit as seen by the capacitor.

 

i solve my homework's rest but in this two questions I don't know what to do ?
My works are just irrelevant because the parellel resistors confuse me.

 

So what do you want from us? For us to just do your work for you?

Do you know what a Thevenin equivalent circuit is?

Do you know how to determine the Thevenin voltage and the equivalent resistance?