Chapter 11: Problem 15
All the points in the set \(\mathbf{S}=\left\\{\frac{\alpha+\mathrm{i}}{\alpha-1} ; \propto \in \mathrm{R}\right\\}(\mathrm{i}=\sqrt{-1})\) lie on a: (a) straight line whose slope is 1 . (b) circle whose radius is 1 . (c) circle whose radius is \(\sqrt{2}\). (d) straight line whose slope is \(-1\).
Short Answer
Step by step solution
Express the Complex Number
Calculate Denominator and Numerator
Simplify Complex Division
Convert to Modulus and Argument
Recognize the Circle
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Locus of a Point
The journey to understanding involves expressing complex numbers in their standard form and exploring how their properties define specific paths. If the condition depends on the modulus (magnitude) or argument (angle), the resulting locus can represent familiar shapes such as circles or straight lines. Understanding the locus helps in visualizing complex number operations and relationships, revealing geometric insights behind algebraic processes.
Using the mathematical expression given in the problem, the set of all possible complex numbers can define a particular path in the complex plane, demonstrating why understanding loci is fundamental in unraveling such equations.
Circle in Complex Plane
To find if a set of complex numbers forms a circle, examine the modulus. If the modulus of the complex expression remains constant, it implies that the numbers lie on a circle. In the original exercise, after rewriting the complex number and simplification, we calculated the modulus \( |z| \) and found it equals 1. This revelation indicates all points form a circle of radius 1 on the complex plane. Hence, identifying such conditions is crucial for recognizing geometric shapes represented by complex expressions.
Modulus of a Complex Number
In the problem, the modulus calculation is pivotal to deciphering the geometric location of points described by the given expression. By finding the modulus and ensuring it equates steadily, we verify whether the expression aligns with a circle's definition or another shape. This property's constancy, when exploring potential values, assists in determining paths like circles or other loci in the plane. Recognizing modulus calculations ensures a strong grasp of the complex number’s impact, dictating both the distance from the origin and potential geometric configurations.