Skip to main content
Ch. 5 - Complex Numbers, Polar Coordinates and Parametric Equations
Blitzer - Trigonometry 3rd Edition
Blitzer3rd EditionTrigonometryISBN: 9780137316601Not the one you use?Change textbook
Chapter 5, Problem 5.RE.57

In Exercises 54–60, convert each polar equation to a rectangular equation. Then use your knowledge of the rectangular equation to graph the polar equation in a polar coordinate system. r = 5 csc θ

Verified step by step guidance
1
Recall the relationships between polar and rectangular coordinates: \(x = r \cos \theta\), \(y = r \sin \theta\), and \(r^2 = x^2 + y^2\).
Given the polar equation \(r = 5 \csc \theta\), rewrite \(\csc \theta\) in terms of sine: \(\csc \theta = \frac{1}{\sin \theta}\), so the equation becomes \(r = \frac{5}{\sin \theta}\).
Multiply both sides of the equation by \(\sin \theta\) to get \(r \sin \theta = 5\).
Use the relationship \(y = r \sin \theta\) to substitute and rewrite the equation as \(y = 5\).
Interpret the rectangular equation \(y = 5\): this represents a horizontal line 5 units above the x-axis. In the polar coordinate system, this corresponds to all points where the vertical coordinate is 5.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
1m
Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Polar and Rectangular Coordinate Systems

Polar coordinates represent points using a radius and an angle (r, θ), while rectangular coordinates use (x, y) positions on a plane. Understanding how these systems relate is essential for converting equations and interpreting graphs in both formats.
Recommended video:
05:32
Intro to Polar Coordinates

Conversion Formulas Between Polar and Rectangular Coordinates

Key formulas link polar and rectangular coordinates: x = r cos θ, y = r sin θ, and r² = x² + y². These allow transformation of equations from one system to the other, enabling easier analysis and graphing.
Recommended video:
06:17
Convert Points from Polar to Rectangular

Trigonometric Functions and Their Reciprocal Identities

The equation involves csc θ, the reciprocal of sin θ (csc θ = 1/sin θ). Recognizing and manipulating these identities helps rewrite the polar equation in terms of x and y, facilitating conversion to rectangular form.
Recommended video:
5:32
Fundamental Trigonometric Identities