Plotting Complex Numbers on an Argand Diagram

[ZedCar]

Homework Statement

Plot 3e^(-i5∏/3) on an Argand Diagram

The Attempt at a Solution

Re(e^iθ) = cosθ = cos(-5∏/3) = 1/2

Im(e^iθ) = sinθ = sin(-5∏/3) = √3 / 2

So I'd go along the x-axis to 1/2 and then upwards in the y-direction to √3 / 2 and plot the point there.

Is this the way you would go about doing this question, or some other method?

Is my answer correct?

Thanks!

P.S. I think I'm supposed to multiply by 3, but at what point do I do this? Exactly what is it that I should multiply by 3?

 

[eumyang]

Re(e^iθ) = cosθ = cos(-5∏/3) = 1/2

Im(e^iθ) = sinθ = sin(-5∏/3) = √3 / 2

As you said, yes, you need to multiply the coordinates by 3. What you have above should be
Re(re^iθ) = r cos θ = ...
Im(re^iθ) = r sin θ = ...

 

[ZedCar]

Ok, thank you eumyang.