Find the distance CD in the given complex variable question

In summary, the conversation discusses different approaches to finding the distance between points ##C## and ##D## on a coordinate plane, specifically using the distance formula and complex numbers. The use of complex numbers is highlighted as a potentially easier method, but it is important to have a good understanding of the argand diagram and vectors. Another approach suggested is to use the relationship ##AD = \frac{1}{2}AB## to find the coordinates of point ##D##. Ultimately, both approaches lead to the same answer of ##CD = √10##.
  • #1
chwala
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Homework Statement
See attached
Relevant Equations
complex variables
This is the problem;

1637818462275.png


Note that i am conversant with the above steps shown in the solution, having said that i realized that we could also borrow from the understanding of gradient and straight lines in finding the distance ##CD##... it follows that the equation of ##BA= -1.5x-0.5##, implying that the co ordinates of ##D(x,y) = (2-3, 4-3) = (-1,1)## and using the distance formula, it follows that;
##CD= √[(3)^2 + (1)^2]##= ##√10## as indicated...

any other approach guys...
 
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  • #2
[tex]\vec{OD}=\frac{1}{2}(\vec{OA}+\vec{OB})=\frac{1}{2}(1-3,-2+4)=(-1,1)[/tex]
[tex]\vec{DC}=(2-(-1),2-1)=(3,1)[/tex]
 
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  • #3
Keeping in mind that the point of the exercise might be for you to get more comfortable with complex numbers, I hope that you are comfortable with their solution. There are often multiple ways to get the same, true, answer. Some are easier than others. You may soon see examples where the use of complex numbers makes solutions much easier.
 
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  • #4
True, the whole idea is to have an understanding of the argand diagram and also the Complex number, say ##Z = x + iy##, then it follows that the Modulus of
##Z =|x+ iy|= √[(x^2 +y^2)]##, and also a good understanding of vectors is required.



 
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  • #5
...but looking at this problem, we could also just use the relationship of ##AD= \frac {1}{2}AB##.
letting the co ordinates of point ##D## be ##(x,y)##, then ##AB= (-3-1)+i(4+2)##
##AB= -4+6i##, therefore ##AD= -2+3i##, also to find the co ordinate of ##AD= (x-1=-2, y+2=3) ##
giving us the co ordinates, ##(-1,1)##
##CD= (-1-2)+ (1-2)i= -3-i##
 

FAQ: Find the distance CD in the given complex variable question

How do I find the distance CD in a complex variable question?

The distance CD in a complex variable question can be found using the distance formula, which is √((x2-x1)^2 + (y2-y1)^2). In this formula, x1 and y1 represent the coordinates of point C, while x2 and y2 represent the coordinates of point D.

What is a complex variable in this context?

A complex variable in this context refers to a number that has both a real and imaginary component. It is typically expressed in the form a + bi, where a is the real part and bi is the imaginary part.

Can I use the Pythagorean theorem to find the distance CD in a complex variable question?

Yes, you can use the Pythagorean theorem to find the distance CD in a complex variable question. This is because the distance formula is derived from the Pythagorean theorem.

What is the significance of finding the distance CD in a complex variable question?

Finding the distance CD in a complex variable question can help determine the magnitude of a complex number or the length of a line segment in the complex plane. It is also an important concept in understanding the geometric properties of complex numbers.

Are there any special cases to consider when finding the distance CD in a complex variable question?

Yes, there are a few special cases to consider when finding the distance CD in a complex variable question. For example, if the points C and D are the same, the distance will be 0. Additionally, if one of the points is the origin (0,0), the distance will be equal to the absolute value of the other point's complex number.

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