De Moivre question (1 Viewer)

[Aysce]

Question is find mod arg form of (-1-i)^10, i found the mod arg form of it using de moivre but answers say that the argument is Pie/2 not - pie/2.

Full answer I received is :

32Cis(-Pie/2).

Confirmation please, muchly appreciated.

 

[AAEldar]

The argument is which simplifies to make it . Raising it to the power 10 and you get which simplifies to and multiplying it by 8 to get it into the required range (remember, multiply in increments of 2).

 

[michaeljennings]

If you type sin(-3xpix10/4) into your calculator using degrees you get 1 so then it must be pi/2

 

[TheCardician]

If you plot the point -1-i on an argand diagram, it'll be in the third quadrant, which means tan is positive. Hence the argument should be positive.