Please help

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[glossy fjord]

The obvious thing to do is check whether the result matches the number it's supposed to.

[strange delta]

Yeah I've tried that and got 1-sqrt (3)/2 i

I found that it should be 4(cos(- π/6) + isin(- π/6)) so I assume it's to do with the square root on r and -1 and sqrt (3) being the wrong way round

[sudden fern]

Note the quadrant the complex number lies in

@strange delta

[strange delta]

Is theta pi/3 not -pi/3 then?

[sudden fern]

What quadrant does the complex number lie in?

[strange delta]

You mean like the top left one?

[sudden fern]

Yea

The second quadrant

[strange delta]

Yeah so theta is positive?

[sudden fern]

Yea

But it's also greater than π/2

And less than π

[strange delta]

Right

[sudden fern]

So not π/3

[strange delta]

Oh yeah

I am so confused

So how do you get any value of theta in the correct range?

[sudden fern]

Imma spoil this

It's π-π/3

Which is 2π/3

[strange delta]

Because?

[sudden fern]

Second quadrant

[strange delta]

What???

[sudden fern]

Because the angle belongs in the second quadrant

[strange delta]

Right

But why do you do π- the angle

Ohhhh

So if it was in the 3rd quadrant

It would be 3 π/2 - the angle?

[sudden fern]

π+reference angle

[strange delta]

Right but when you do it with than angle you get 1-sqrt(3)i

So does r have to be negative when in quadrant 2 or 3?

[sudden fern]

Well the complex number is in quadrant 2

So you shouldnt use an angle in quadrant 3

[strange delta]

Oh I used 2 π- π/3 for some reason😭

Mb

Alright thank you

+close

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