Calculating Modulus and Argument of a Complex Number | Homework Question

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SUMMARY

The discussion focuses on calculating the modulus and argument of the complex number z = cis @, where @ is acute. The modulus of z is established as 1, indicating that z lies on the unit circle. The final results for the modulus of z-1 are given as 2 sin(@/2) and the argument as (@/2) + (π/2). Visual representation through graphing is emphasized as a crucial method for understanding the problem, aiding in the comprehension of the relationships between angles and shapes in the complex plane.

PREREQUISITES
  • Understanding of complex numbers and their representation in polar form.
  • Knowledge of modulus and argument calculations for complex numbers.
  • Familiarity with trigonometric functions, specifically sine and tangent.
  • Ability to interpret graphical representations of complex numbers in the complex plane.
NEXT STEPS
  • Study the properties of the unit circle in relation to complex numbers.
  • Learn about the geometric interpretation of complex number operations.
  • Explore the derivation of the modulus and argument formulas for complex numbers.
  • Investigate the use of graphical tools for visualizing complex number transformations.
USEFUL FOR

Students studying complex analysis, mathematics educators, and anyone looking to deepen their understanding of complex number operations and their graphical interpretations.

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Homework Statement



If z = cis @ where @ is acute, determine the modulus and argument of z-1


Homework Equations





The Attempt at a Solution



As the moudlus of z is 1 z lies on the unit circle. And I can not think of anything more. I drew a graph to see how z-1 seems like in graph and stucked.
Help me please!
 
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The modulus of x + iy is √(x² + y²) and the argument is tan-1(y/x). Draw the vector in the complex plane to see why.
 
That I know; but this thing is little different from the normal quetions where the number is multiplied to z such as -z, 2z etc which i can use that formula but here i think i should know some angles and shape of graph
I saw the answer and it was
moduls = 2 sin (@/2) argument = (@/2) + (pi/2)
 
It's possible to do using just the formulas I wrote, but it's easier to do pictorially. Look at the attachment:

http://img99.imageshack.us/img99/86/picqrv.jpg
 
Last edited by a moderator:
Wow i also drew some similar graph but couldn't understand what to do with that but by drawing the line at the middle everything become clear.
Thankyou so much!
 
No problem.
 

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