Chapter 1: Problem 156
For the following exercises, describe the graph of each polar equation. Confirm each description by converting into a rectangular equation. $$r=\sec \theta$$
Short Answer
Expert verified
The graph is a vertical line at \( x = 1 \).
Step by step solution
01
Understand the Polar Equation
The given polar equation is \( r = \sec \theta \). In polar coordinates, \( r \) represents the radial distance from the origin, and \( \theta \) represents the angle measured counterclockwise from the positive x-axis. The secant function is the reciprocal of the cosine function, which means \( \sec \theta = \frac{1}{\cos \theta} \).
02
Express r in Terms of Trigonometric Functions
Let us express \( r \) using cosine: \( r = \frac{1}{\cos \theta} \). This can be rewritten as \( r \cos \theta = 1 \).
03
Convert to Rectangular Coordinates
In polar coordinates, \( x = r \cos \theta \) and \( y = r \sin \theta \). From Step 2, we have \( r \cos \theta = 1 \), which in rectangular coordinates becomes \( x = 1 \).
04
Interpret the Rectangular Equation
The equation \( x = 1 \) is a vertical line in the Cartesian coordinate plane. This means the polar equation \( r = \sec \theta \) describes a vertical line at \( x = 1 \).
05
Graph the Polar Equation
The graph of the polar equation \( r = \sec \theta \) will be a vertical line where each point on the line has an x-coordinate of 1. This confirms the conversion to rectangular coordinates, as any point on the line at \( x = 1 \) satisfies the original polar equation.
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, also known as Cartesian coordinates, are a straightforward way to pinpoint any location in a plane. They're defined by two numbers:
expression \( x = 1 \). This describes a vertical line on the Cartesian plane, where every point has an \( x \)-coordinate of 1 regardless of the \( y \)-value.
- \( x \): the horizontal position on the plane.
- \( y \): the vertical position on the plane.
expression \( x = 1 \). This describes a vertical line on the Cartesian plane, where every point has an \( x \)-coordinate of 1 regardless of the \( y \)-value.
Polar Equations
Polar equations provide a unique way to describe curves in a plane through radial distance and angular measurement. The polar coordinates are determined by:
- \( r \): the radial distance from the origin.
- \( \theta \): the angle from the positive x-axis.
Trigonometric Functions
Trigonometric functions are crucial when working with polar coordinates as they connect angle measurements with distances, simplifying various mathematical conversions.
- \( \cos \theta \): relates the adjacent side over hypotenuse in a right triangle.
- \( \sec \theta \): is the reciprocal of \( \cos \theta \), so \( \sec \theta = \frac{1}{\cos \theta} \).
Graphing
Graphing is a fundamental tool to visualize equations, be they in polar or rectangular form. For effective graphing:
- Understand the equations you want to plot.
- Determine whether to plot in polar coordinates (curves, circles) or Cartesian coordinates (straight lines, simple parabolas).