Chapter 9: Problem 61
Convert the point given in spherical coordinates to (a) rectangular coordinates and (b) cylindrical coordinates. $$ \left(8, \frac{\pi}{4}, \frac{3 \pi}{4}\right) $$
Short Answer
Expert verified
Rectangular coordinates: (4, 4, -4√2); Cylindrical coordinates: (4√2, π/4, -4√2).
Step by step solution
01
Understanding Spherical Coordinates
Spherical coordinates are given as \((
ho, heta, ext{ and } heta)\), where \(\rho\) is the radial distance from the origin, \(\phi\) is the polar angle measured from the positive z-axis, and \(\theta\) is the azimuthal angle in the xy-plane from the positive x-axis.
02
Converting to Rectangular Coordinates
Rectangular (Cartesian) coordinates \((x, y, z)\) are determined by the following formulas:\[ x = \rho \sin \phi \cos \theta \]\[ y = \rho \sin \phi \sin \theta \]\[ z = \rho \cos \phi \]Substitute the given values \(\rho = 8\), \(\phi = \frac{3\pi}{4}\), and \(\theta = \frac{\pi}{4}\) into these formulas:\[ x = 8 \sin\left(\frac{3\pi}{4}\right) \cos\left(\frac{\pi}{4}\right) \]\[ y = 8 \sin\left(\frac{3\pi}{4}\right) \sin\left(\frac{\pi}{4}\right) \]\[ z = 8 \cos\left(\frac{3\pi}{4}\right) \]
03
Calculating x, y, and z
First, calculate each sine and cosine value:- \(\sin\left(\frac{3\pi}{4}\right) = \frac{\sqrt{2}}{2}\)- \(\cos\left(\frac{3\pi}{4}\right) = -\frac{\sqrt{2}}{2}\)- \(\cos\left(\frac{\pi}{4}\right) = \frac{\sqrt{2}}{2}\)- \(\sin\left(\frac{\pi}{4}\right) = \frac{\sqrt{2}}{2}\)Now, substitute these values into the rectangular coordinate equations:\[ x = 8 \times \frac{\sqrt{2}}{2} \times \frac{\sqrt{2}}{2} = 8 \times \frac{1}{2} = 4 \]\[ y = 8 \times \frac{\sqrt{2}}{2} \times \frac{\sqrt{2}}{2} = 8 \times \frac{1}{2} = 4 \]\[ z = 8 \times -\frac{\sqrt{2}}{2} = -4\sqrt{2} \]So, the rectangular coordinates are \((4, 4, -4\sqrt{2})\).
04
Converting to Cylindrical Coordinates
Cylindrical coordinates \((r, \theta, z)\) consist of the radial distance \(r\) from the z-axis, angle \(\theta\), and the same z as in rectangular coordinates. The conversions to cylindrical are:\[ r = \rho \sin \phi \]\[ z = \rho \cos \phi \]Given \(\rho = 8\) and \(\phi = \frac{3\pi}{4}\), calculate:\[ r = 8 \times \sin\left(\frac{3\pi}{4}\right) = 8 \times \frac{\sqrt{2}}{2} = 4\sqrt{2} \]The angle \(\theta\) remains the same and \(z\) is calculated from previous:So, the cylindrical coordinates are \((4\sqrt{2}, \frac{\pi}{4}, -4\sqrt{2})\).
Unlock Step-by-Step Solutions & Ace Your Exams!
-
Full Textbook Solutions
Get detailed explanations and key concepts
-
Unlimited Al creation
Al flashcards, explanations, exams and more...
-
Ads-free access
To over 500 millions flashcards
-
Money-back guarantee
We refund you if you fail your exam.
Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Spherical Coordinates
Spherical coordinates are a way of representing points in space using a set of three different values. Unlike the regular x, y, and z from rectangular coordinates, spherical coordinates involve the following elements:
- \(\rho\) (rho), which is the radial distance from the origin to the point.
- \(\phi\) (phi), the polar angle from the positive z-axis.
- \(\theta\) (theta), the azimuthal angle in the xy-plane measured from the positive x-axis.
Rectangular Coordinates
Rectangular coordinates, also known as Cartesian coordinates, represent positions in space using three perpendicular axes. Each point in this system is defined by three values: \((x, y, z)\). This is the most common coordinate system and underpins much of the geometry and algebra we learn.
To convert from spherical to rectangular coordinates, we use the following equations:
To convert from spherical to rectangular coordinates, we use the following equations:
- \[ x = \rho \sin \phi \cos \theta \]
- \[ y = \rho \sin \phi \sin \theta \]
- \[ z = \rho \cos \phi \]
Cylindrical Coordinates
Cylindrical coordinates mix elements of both spherical and rectangular systems to describe a point's position in a three-dimensional space. They are structured as \((r, \theta, z)\) where:
- \(r\) is the radial distance from the z-axis in the xy-plane.
- \(\theta\) is the same azimuthal angle as in spherical coordinates.
- \(z\) represents the height above the xy-plane, equivalent to the z in rectangular coordinates.
- \[ r = \rho \sin \phi \]
- The \(\theta\) value remains the same.
- \[ z = \rho \cos \phi \]