Polar Coordinates to evaluate integrals

In summary, the problem asks to use polar coordinates to evaluate a unit circle (C) around a fixed point (Z0) in the complex plane. The conversation mentions using polar integrals and the Cauchy integral formula to find the residues and evaluate the integral. The final answer is given as 2∏i(aZ02 + bZ0 + c). The participants also discuss the need for practice to better understand the theory.
  • #1
Fixxxer125
41
0

Homework Statement


Use Polar coordinates to evaluate
2eydkky.png
were C denotes the unit circle about a fixed point Z0 in the complex plane



The Attempt at a Solution


I've only used polar integrals to convert an integral in sin and cos into one in therms of z, find the residues and then use the residue theorum to evaluate the integral so I am not really sure where to go with this question? Any help would be greatly appreciated!
 
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  • #2
Let [itex]z= z_0+ e^{i\theta}[/itex].
 
  • #3
Have I done it correctly if I end up with a final answer of
2∏i(aZ02 + bZ0 + c)
Thanks!
 
  • #4
Yes, in fact there is the "Cauchy integral formula" that says
[tex]\oint \frac{f(z)}{z-z_0} dz= 2\pi if(z_0)[/tex]

Perhaps this problem was intended as an introduction to that.
 
  • #5
Ah yes we have done that previously, I think I just need to do practise questions to bring all the theory together. Cheers
 

1. What are polar coordinates?

Polar coordinates are a system of representing points in a plane using a distance from a fixed point (the pole) and an angle from a fixed direction (the polar axis).

2. How are polar coordinates used to evaluate integrals?

Polar coordinates are useful for evaluating integrals when the region of integration is better described in terms of a radius and angle rather than x and y coordinates. This is often the case for symmetric shapes such as circles, ellipses, and sectors.

3. Can any integral be evaluated using polar coordinates?

No, not all integrals can be evaluated using polar coordinates. The region of integration must have a defined shape, such as a circle or sector, for polar coordinates to be applicable.

4. What is the process for converting from Cartesian coordinates to polar coordinates?

To convert from Cartesian coordinates (x, y) to polar coordinates (r, θ), the following formulas can be used: r = √(x^2 + y^2) and θ = arctan(y/x). Keep in mind that θ is measured counterclockwise from the positive x-axis.

5. Are there any advantages to using polar coordinates over Cartesian coordinates for evaluating integrals?

Yes, there are some cases where using polar coordinates can simplify the process of evaluating integrals. This is particularly true for integrals involving symmetric shapes, as mentioned earlier. Additionally, polar coordinates can also be useful for evaluating integrals involving curves that are difficult to express in Cartesian coordinates.

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