Chapter 9: Problem 41
Convert the point given in rectangular cocrdinates to cylindrical coondinates. $$ (-\sqrt{2}, \sqrt{6}, 2) $$
Short Answer
Expert verified
The cylindrical coordinates are \((2\sqrt{2}, \frac{2\pi}{3}, 2)\).
Step by step solution
01
Identify the Rectangular Coordinates
The point given in rectangular coordinates is \((x, y, z) = (-\sqrt{2}, \sqrt{6}, 2)\).
02
Calculate the Radial Distance
To find the radial distance \(r\) for cylindrical coordinates, use the formula:\[r = \sqrt{x^2 + y^2}\].Substitute the values:\(r = \sqrt{(-\sqrt{2})^2 + (\sqrt{6})^2} = \sqrt{2 + 6} = \sqrt{8} = 2\sqrt{2}\).
03
Find the Angle \(\theta\)
Calculate the angle \(\theta\) in the xy-plane with the formula:\[\theta = \tan^{-1}\left(\frac{y}{x}\right)\].For our given coordinates:\(\theta = \tan^{-1}\left(\frac{\sqrt{6}}{-\sqrt{2}}\right) = \tan^{-1}\left(-\sqrt{3}\right)\).The angle depends on the quadrant; since \(x < 0\) and \(y > 0\), the point is in the second quadrant. Thus, \(\theta = \pi - \frac{\pi}{3} = \frac{2\pi}{3}\).
04
Determine the z-component
The \(z\)-coordinate remains unchanged in cylindrical coordinates. Therefore, \(z = 2\).
05
Assemble the Cylindrical Coordinates
Combine \(r\), \(\theta\), and \(z\) to express the point in cylindrical coordinates:\((r, \theta, z) = (2\sqrt{2}, \frac{2\pi}{3}, 2)\).
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.
Rectangular Coordinates
Rectangular coordinates provide a way of pinpointing a location in a 3-dimensional space using three values:
- The x-coordinate which represents the horizontal position towards the east or west.
- The y-coordinate which specifies the vertical position towards the north or south.
- The z-coordinate which gives the height position upwards or downwards.
Radial Distance
In cylindrical coordinates, radial distance measures how far a point is from the z-axis, which acts as the centerline. This distance is denoted by the letter \(r\).The radial distance is found using the Pythagorean theorem: \[r = \sqrt{x^2 + y^2}\].This formula works because, on a flat plane at any height (constant \(z\)), the position is akin to describing a right triangle where \(x\) and \(y\) are the perpendicular sides. In this exercise:
- The x-value is \(-\sqrt{2}\)
- The y-value is \(\sqrt{6}\)
- Using these values, the radial distance is calculated to be \(2\sqrt{2}\).
Angle Calculation
In cylindrical coordinates, the angle \(\theta\) is used to specify the direction in the xy-plane from the positive x-axis.This angle is crucial for determining the rotational position around the z-axis. For finding the angle:\[\theta = \tan^{-1}\left(\frac{y}{x}\right)\]However, it’s important to consider the quadrant where \(x\) and \(y\) lie to accurately determine the angle.For this example:
- \(x = -\sqrt{2}\) is negative, and
- \(y = \sqrt{6}\) is positive, placing the point in the second quadrant.
Coordinate Conversion
Converting from rectangular to cylindrical coordinates involves transitioning from the \((x, y, z)\) format into \((r, \theta, z)\). Each component plays a specific role:
- \(r\) represents the radial distance, or how far the point is from the z-axis, calculated through the horizontal (x-y plane) components.
- \(\theta\) gives the angle from the positive x-axis, crucial for direction in the xy plane.
- The z-component remains unchanged, ensuring vertical alignment with the original point.
- The example calculation produces the cylindrical coordinates \((2\sqrt{2}, \frac{2\pi}{3}, 2)\), indicating that the point is still at the same height (z) while rotating and shifting its radial position.