Operations on complex numbers in polar form

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Now Playing:Operations on complex numbers in polar form – Example 1a
Examples
  1. Multiplying complex numbers in polar form
    1. 4(cos(5π3)+isin(5π3))8(cos(2π3)+isin(2π3)) 4(\cos(\frac{5\pi}{3})+i \sin(\frac{5\pi}{3})) \cdot 8(\cos(\frac{2\pi}{3})+i \sin(\frac{2\pi}{3}))

    2. (cos(170)+isin(170))5(cos(45)+isin(45)) (\cos(170^{\circ})+i \sin(170^{\circ}))\cdot 5(\cos(45^{\circ})+i \sin(45^{\circ}))

    3. 3(cos(π)+isin(π))(cos(π5)+isin(π5))6(cos(2π3)+isin(2π3))3(\cos(\pi)+i \sin(\pi))\cdot(\cos(\frac{\pi}{5})+i \sin(\frac{\pi}{5}))\cdot6(\cos(\frac{2\pi}{3})+i \sin(\frac{2\pi}{3}))

Introduction to imaginary numbers
Notes
Let's find out how to perform some basic operations on complex numbers in polar form! We will briefly introduce the notion of the exponential form of a complex number, then we will focus on multiplication and division on complex numbers in polar form.
Note:

Polar form
real part
a=zcosθa=|z|\cos \theta
imaginary part
b=zsinθb=|z|\sin \theta
z=z(cosθ+isinθ)z=|z|(\cos \theta+i\sin \theta)

When …
Multiplying: multiply the absolute values, and add the angles
Dividing: divide the absolute values, and subtract the angles

Exponential form
z=zeiθz=|z|e^{i \theta}