Question

modulus of Z= -7i .complex numbers

Answer 1

I hope you have understood

Answer 2

An argument of the complex number z= x + iy, denoted arg(z), is defined in two equivalent ways: Geometrically, in the complex plane, as the angle φ from the positive real axis to the vector representing z. The numeric value is given by the angle in radians and is positive if measured counter clockwise.