Use the following relations to solve problem 1 and 2:
z = x + jy Rectangular form
z = r/ϕ Polar form (9.15)
z = re^{jϕ} Exponential form
The relationship between the rectangular form and the polar form is shown in Fig. 9.6, where the x axis represents the real part and the y axis represents the imaginary part of a complex number. Given x and y, we can get r and ϕ as
r = √(x² + y²), ϕ = tan⁻¹(y/x) (9.16a)
On the other hand, if we know r and ϕ, we can obtain x and y as
x = r cos ϕ, y = r sin ϕ (9.16b)
Thus, z may be written as
z = x + jy = r/ϕ = r(cos ϕ + j sin ϕ) (9.17)
Addition and subtraction of complex numbers are better performed in rectangular form; multiplication and division are better done in polar form. Given the complex numbers
z₁ = x₁ + jy₁ = r₁/ϕ₁
z₂ = x₂ + jy₂ = r₂/ϕ₂
the following operations are important.
Addition:
z₁ + z₂ = (x₁ + x₂) + j(y₁ + y₂) (9.18a)
Subtraction:
z₁ - z₂ = (x₁ - x₂) + j(y₁ - y₂) (9.18b)
Multiplication:
z₁z₂ = r₁r₂/ϕ₁ + ϕ₂ (9.18c)
Division:
z₁/z₂ = r₁/r₂/ϕ₁ - ϕ₂ (9.18d)
Reciprocal:
1/z = 1/r/-ϕ (9.18e)
Square Root:
√ z = √ r/ϕ/2 (9.18f)
Complex Conjugate:
z* = x - jy = r/-ϕ = re⁻ᴶᵠ (9.18g)
Note that from Eq. (9.18e),
1/j = -j (9.18h)
Alexander, Charles K. Fundamentals of electric circuits / Charles K. Alexander, Matthew N. O. Sadiku. — 5th ed.p. cm