I assume you mean
MAGNITUDE:
Magnitude of a complex number is denoted by and is defined as
Geometrically, that is, on the Argand plane, this denotes the distance of the complex number from the origin.
ARGUMENT:
Argument of a complex number is denoted by and is defined as
Where and sgn is the signum function.
Geometrically, that is, on the Argand plane, this denotes the angle made by the line joining the origin and the complex number with the positive direction of the x axis.
Aliter:
If you know cube roots of unity and their positions in th argand plane.
Then observe that
Thus the complex number is .
But we know that the cube roots of unity are on the unit circle and that they are distributed over the unit circle at to each other. 1 is on the real line. is at an angle to the x-axis. is at an angle to the x-axis.
Mathematically they mean
Lets use these facts:
Note the correction above.
I am sure that the question deals with this number: .
“Multitude” must mean absolute value (distance from origin): .
The argument is the angle the ray from the origin through the number makes with the positive real axis.
In doing this problem here are two useful facts: .