very basic complex # question (1 Viewer)

[...]

erk..

ummm..

find the argument of z= -1-i

so argument is the angle right?
umm...yea...somehow the lecturer said its @=-3(pi)/4

can someone explain why?

 

[:: ck ::]

ASTC rule

so if u draw it on the argand diagram it is in the 3rd quadrant

i.e : the angle from -pi + @ (angle is @)

so to find @ we use tan-1 (1/1) = pi/4 or 45 degrees

thus the argument is -pi + pi/4

which is -3pi/4

 

[...]

ok, this might sound retarded..but umm..

why is -pi +@


brain dead atm...

 

[Calculon]

Originally posted by ...
ok, this might sound retarded..but umm..

why is -pi +@


brain dead atm...

because we know its in the 3rd quadrant and the rule for the 3rd quadrant is pi + @ , but since on argand diagrams there is a domain of -pi < @ < pi, and pi + @ would be outside that domain, we use -pi + @

 

[CM_Tutor]

Actually, saying that the argument of -1 - i is 5 * pi / 4 is valid, its only the principal argument that is restricted to the domain indicated by Calculon.

So, either 5 * pi / 4 or -3 * pi / 4 would be valid answers.

 

[Calculon]

Well thankyou Mr. Technical