Convert each of the complex numbers given in Exercises 3 to 8 in the polar form:

– 1 – i

Let – 1 = r cos θ and – 1 = r sin θ ……….(i)


Squaring both sides, we get


1= r2 cos2 θ and 1 = r2 sin2 θ


Adding both the equations, we get


1 + 1 = r2 cos2 θ + r2 sin2 θ


2 = r2 (cos2 θ + sin2 θ)


2 = r2 or r2 = 2 [ sin2 θ + cos2 θ = 1]


r = 2


r = 2 (conventionally, r>0)


Substituting r = √2 in (i), we get


– 1 = √2 cos θ and – 1 = √2 sin θ




We know that the complex number 1 i lies in the third quadrant and the value of the argument lies between - π and π, i.e. - π < θ ≤ π.




As we know that the polar representation of a complex number z = x + iy is


z = r (cos θ + i sin θ) where is the modulus of the complex number and θ is the argument of the complex number, denoted by arg z.


So, the required polar form is .


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