Please help me with this question of complex numbers

[Priya]

I have attached the question and my answer. The modulus of u and u^2 and the argument of u is right according the mark scheme. Can you tell me what is wrong with the argument of u^2?

The answer of argument of u^2 is pi/2

I am really grateful for all the help. Thank you so much!!

[astarmathsandphysics]

I think they want the ar in the range 0 to 2pi.

So do 2pi+(-3pi/2)=pi/2

[Priya]

Thank you for the help =)

Just to confirm... Since it is not stated here, should I assume that for such questions, I should give my
answer between 0 and 2pi.

Thanks again.

[astarmathsandphysics]

Yes I would. Since they did not tell you to give your answe between o and 2pi, -3/2pi should get full marks too.

[blablabla17]

hey i just learnt it today...this morning...

my teacher asked us to rmb this formula...

( z)^n= r^N(COS N angle + i sin N angle)...

follow this formula then u will get the answer...

and i think what astar said is not right...

sorry for saying that...just follow the formula my teacher gave

[astarmathsandphysics]

The formula is another method. I cant post fully on this as i am abroad on a mobile phone