Math-Vectors-Phasors

[wdcw]

Gday everyone,

I have a question I need to answer, just wondering if someone can help me out please.

The question is:

( Determine the load star point to earth voltage & the C phase to star point voltage of a 415v 3-phase 4 wire supply system if the following voltages are measured, when the neutral is disconnected.

A phase to star point 280v
B phase to star point 200v )

I have drawn a phasor diagram (Attached) to get the C phase to star point voltage, could someone have a look & see if I have drawn this correctly?

I can't seem to find a way to get the star point to earth voltage, need some advice on this one?

Cheers