Rect. and Polar with complex numbers

In summary, the conversation is about finding the square root of a complex number B in both rectangular and polar notation. The suggested method is to multiply the square root of B by itself to get B, and then use the magnitude and tangent to find the angle. The conversation also mentions using a calculator for the rectangular form, but asks for a method without a calculator. The final response suggests looking at the Wikipedia page on square roots of negative and complex numbers for further clarification.
  • #1
krnhseya
103
0

Homework Statement



B= 4-j2. Find [tex]\sqrt{B}[/tex] in rectangular and polar notation.

Homework Equations



n/a

The Attempt at a Solution



i can figure out that in rectangular form by using the calculator and converting those back into polar form but how can i do this without calculator?
 
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  • #2
When you multiply two complex numbers together, their magnitudes are multiplied and their angles are added.

- Warren
 
  • #3
magnitude of B = sqrt(4^2 + (-2)^2)
and use tangent to find the angle.

but i am asked to find square root.
 
  • #4
You're looking for a complex number, the square root of B. You know that if you multiply the square root of B by itself, you get B. Find the complex number that, when multiplied by itself (using the "rule" I have already given you), results in B.

- Warren
 
  • #5
...?
 
  • #6
sorry but last 2 posts don't help me at all;
it's quite obvious that sqrt(b) ^2 = b...and i know how to find magnitude and angle once i get it in forms of X + yj
 
  • #7

1. What is the difference between rectangular and polar form with complex numbers?

Rectangular form is when a complex number is expressed as a combination of a real number and an imaginary number in the form a + bi, where a is the real part and bi is the imaginary part. On the other hand, polar form is when a complex number is expressed in terms of its magnitude (r) and angle (θ) in the form r(cos θ + isin θ).

2. How do you convert a complex number from rectangular to polar form?

To convert a complex number from rectangular to polar form, you can use the following formula: r = √(a² + b²) and θ = tan⁻¹(b/a). This will give you the magnitude and angle of the complex number, which can then be expressed as r(cos θ + isin θ).

3. Can you add or subtract complex numbers in polar form?

Yes, you can add or subtract complex numbers in polar form by converting them to rectangular form, performing the operation, and then converting back to polar form. Alternatively, you can use the formula z₁ + z₂ = r₁(cos θ₁ + isin θ₁) + r₂(cos θ₂ + isin θ₂) = (r₁ + r₂)(cos(θ₁ + θ₂) + isin(θ₁ + θ₂)) to add two complex numbers in polar form directly.

4. How do you multiply or divide complex numbers in polar form?

To multiply two complex numbers in polar form, you can use the formula z₁z₂ = r₁r₂(cos(θ₁ + θ₂) + isin(θ₁ + θ₂)). To divide two complex numbers in polar form, you can use the formula z₁/z₂ = r₁/r₂(cos(θ₁ - θ₂) + isin(θ₁ - θ₂)).

5. Can you graph complex numbers in polar form?

Yes, you can graph complex numbers in polar form by converting them to rectangular form and plotting them on the complex plane. The magnitude of the complex number will be the distance from the origin, and the angle will determine the direction of the complex number on the plane.

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