Chapter 10: Problem 19
Find the Cartesian equations of the graphs of the given polar equations. $$ r \cos \theta+3=0 $$
Short Answer
Expert verified
The Cartesian equation is \( x = -3 \).
Step by step solution
01
Understand the Polar Equation
The given polar equation is \( r \cos \theta + 3 = 0 \). This is a polar equation where \( r \) is the radius (distance from the origin) and \( \theta \) is the angle. Our goal is to convert this into a Cartesian equation using the variables \( x \) and \( y \).
02
Use Polar to Cartesian Conversion
Recall the conversion formulas: \( x = r \cos \theta \) and \( y = r \sin \theta \). Substitute \( x = r \cos \theta \) into the polar equation \( r \cos \theta + 3 = 0 \).
03
Substitute and Simplify
Substitute for \( r \cos \theta \): \( x + 3 = 0 \). This simplifies to \( x = -3 \).
04
Identify the Cartesian Equation
The equation \( x = -3 \) is the Cartesian equation of the line. It represents a vertical line in the coordinate plane, since the value of \( y \) can be any real number.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
polar_coordinates
Polar coordinates are a way to represent a point in the plane using a distance and an angle. It's a system that's particularly handy when dealing with problems involving circular or rotational symmetry.
- The key components are the radius \( r \), which stretches from the origin to the point, and \( \theta \), the angle formed with the positive x-axis.
- These values tell you exactly where the point is, much like how Cartesian coordinates use \( x \) and \( y \) axes.
polar_to_Cartesian_conversion
Converting from polar coordinates to Cartesian coordinates involves using simple trigonometric relationships between the systems. The relations are derived from the components of a right triangle formed by \( r \), about the origin, and lines parallel to the axes.
- The equations we use are \( x = r \cos \theta \) and \( y = r \sin \theta \).
- These expressions decompose the radius \( r \) into how far 'up' and 'across' the point lies from the origin.
graphing_equations
Graphing equations in Cartesian coordinates offers a visual representation of mathematical relationships. Once we transform polar equations, like \( r \cos \theta + 3 = 0 \), into Cartesian form, they become easier to visualize, especially if you're familiar with the standard coordinate axes.
- The equation \( x = -3 \) indicates a vertical line, a straightforward Cartesian plot where every point has an \( x \)-value of -3, regardless of the \( y \)-value.
- This technique helps in easily assessing intercepts, slopes, and other properties visible directly on the graph.