Chapter 9: Problem 12
Graph the complex number and find its modulus. $$ -1-\frac{\sqrt{3}}{3} i $$
Short Answer
Expert verified
The modulus is \(\frac{2\sqrt{3}}{3}\), and it is plotted at \((-1, -\frac{\sqrt{3}}{3})\).
Step by step solution
01
Understand the Complex Number
The complex number given is \(-1 - \frac{\sqrt{3}}{3} i\). It is written in the form \(a + bi\), where \(a\) is the real part and \(b\) is the imaginary part. Here, \(a = -1\) and \(b = -\frac{\sqrt{3}}{3}\).
02
Plot the Complex Number on the Argand Plane
To graph the complex number, we plot it on the Argand plane where the x-axis represents the real part and the y-axis represents the imaginary part. The point \((-1, -\frac{\sqrt{3}}{3})\) corresponds to the complex number \(-1 - \frac{\sqrt{3}}{3} i\).
03
Calculate the Modulus
The modulus of a complex number \(a + bi\) is given by \(|a + bi| = \sqrt{a^2 + b^2}\). Substitute \(a = -1\) and \(b = -\frac{\sqrt{3}}{3}\) into the formula: \[\left|-1 - \frac{\sqrt{3}}{3} i\right| = \sqrt{(-1)^2 + \left(-\frac{\sqrt{3}}{3}\right)^2}.\]This simplifies to: \[\left|-1 - \frac{\sqrt{3}}{3} i\right| = \sqrt{1 + \frac{1}{3}} = \sqrt{\frac{4}{3}} = \frac{2}{\sqrt{3}} = \frac{2\sqrt{3}}{3}.\]
04
Conclusion
The modulus of the complex number \(-1 - \frac{\sqrt{3}}{3} i\) is \(\frac{2\sqrt{3}}{3}\). It is plotted at the point \((-1, -\frac{\sqrt{3}}{3})\) on the Argand plane.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Argand Plane
In the study of complex numbers, the Argand Plane provides a visual way to represent complex numbers. This is similar to a Cartesian coordinate plane but is used to map complex numbers. In the Argand Plane:
approaches used here makes the visualization of complex numbers more intuitive.
- The horizontal axis, or x-axis, represents the real part of the complex number.
- The vertical axis, or y-axis, represents the imaginary part of the complex number.
approaches used here makes the visualization of complex numbers more intuitive.
Modulus of Complex Numbers
The modulus of a complex number gives us an idea of its "size" or "distance" from the origin in the Argand Plane. Mathematically, for a complex number \(z = a + bi\), the modulus \(|z|\) is calculated using the formula:\[ |z| = \sqrt{a^2 + b^2} \]Think of it as the hypotenuse in a right triangle -- with \(a\) and \(b\) as the other sides. This distance measurement is crucial for understanding complex number magnitude. For the number \(-1 - \frac{\sqrt{3}}{3} i\), substituting \(a = -1\) and \(b = -\frac{\sqrt{3}}{3}\) into the formula, we find:\[ | -1 - \frac{\sqrt{3}}{3} i | = \sqrt{1 + \frac{1}{3}} \]Simplifying leads to:\[ | -1 - \frac{\sqrt{3}}{3} i | = \frac{2\sqrt{3}}{3} \]Understanding the modulus is key to grasping the scale of complex numbers and how they relate spatially to one another.
Graphing Complex Numbers
Graphing complex numbers is a systematic process that involves plotting their components on the Argand Plane. Each complex number consists of a real part and an imaginary part, expressed as \(a + bi\). When graphing:
- Identify the real part \(a\) and the imaginary part \(b\) from the complex number.
- On the Argand Plane, plot a point at location \( (a, b) \).
- The real part \(-1\) places the point one unit left of the origin along the x-axis.
- The imaginary part \(-\frac{\sqrt{3}}{3}\) determines its position along the y-axis below the x-axis.