Question

Z=3-4i then

Answer 1

What about it?

Z is a complex number, in quad IV of the Argand plane.
Z = 3 - 4i
= 5(cosθ + isinθ) , where tanθ = -4/3

in radians: θ = 5.3559
so Z = 5(cos5.3559 + isin5.3559)

in degrees: θ = 306.8699°
Z = 5(cos306.8699° + isin306.8699°)