Chapter 11: Problem 82
Convert the equation from polar coordinates into rectangular coordinates. $$ \theta=\pi $$
Short Answer
Expert verified
The rectangular equation is \( y = 0 \).
Step by step solution
01
Understand the Polar Equation
The given polar equation is \( \theta = \pi \). In polar coordinates, the angle \( \theta \) is the angle from the positive x-axis in the counter-clockwise direction.
02
Recall Polar to Rectangular Transformation
To convert polar coordinates \((r, \theta)\) into rectangular coordinates \((x, y)\), we use the transformations: \( x = r \cos \theta \) and \( y = r \sin \theta \). We now need to analyze the given equation \( \theta = \pi \).
03
Analyze the Angle \(\theta=\pi\)
When \( \theta = \pi \), the angle points directly opposite to the positive x-axis, which lies on the negative x-axis. In polar coordinates, all points corresponding to \( \theta = \pi \) lie on this line.
04
Set Up Rectangular Coordinates Equation
Since \( \theta = \pi \) implies a line along the negative x-axis, it can be expressed in rectangular form by setting \( y=0 \). Thus, any point on this line has \( x=r \cos(\pi) = -r \).
05
Finalize the Rectangular Equation
The rectangular representation of \( \theta = \pi \) is the line \( y = 0 \) and \( x \leq 0 \) since \( r \) could be any non-negative value indicating a point on the negative x-axis. So, the equation in rectangular coordinates is simply \( y = 0 \).
06
Conclusion
The rectangular coordinate form represents a horizontal line along the x-axis, negative direction, so the equation simplifies to \( y = 0 \) with \( x \leq 0 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Polar Coordinates
Polar coordinates represent a point in a plane based on its distance from a reference point and the angle from a reference direction. In this system, each point is determined by two values: the radial coordinate, often denoted as \( r \), and the angular coordinate, \( \theta \).
- The radial distance \( r \) is the distance from the point to the origin of the coordinate system.
- The angle \( \theta \) is measured from the positive x-axis, moving counter-clockwise.
Rectangular Coordinates
Rectangular coordinates, often referred to as Cartesian coordinates, locate a point in a plane through two perpendicular axes, usually labeled as the x-axis and y-axis. Each point in this system is represented by an ordered pair \((x, y)\).
- Here, \( x \) is the horizontal distance from the origin, measured along the x-axis.
- \( y \) represents the vertical distance from the origin, measured along the y-axis.
Angle Transformation
Angle transformation involves converting or utilizing angles from one coordinate system into another. In polar coordinates, the angle \( \theta \) plays a crucial role in defining the position. In the exercise, we consider the angle \( \theta = \pi \), which corresponds to the line that lies directly opposite the positive x-axis, effectively on the negative x-axis. This means that the entire line described by \( \theta = \pi \) in polar coordinates aligns horizontally along the x-axis's negative side, where the vertical component \( y \) remains zero. Understanding angle transformation is vital in accurately switching between coordinate systems. It helps in tracing the path or trajectory of an object relative to a fixed origin.
Coordinate Transformation
Coordinate transformation is the process of converting coordinates from one system to another to analyze and understand the geometric representation interchangeably.
- For transforming from polar to rectangular coordinates, we use the transformations \( x = r \cos \theta \) and \( y = r \sin \theta \).
- In the given problem, the expression \( \theta = \pi \) is analyzed by these transformations to conclude that \( y = 0 \) and \( x \leq 0 \).