In Exercises 21–40, eliminate the parameter t. Then use the rectangular equation to sketch the plane curve represented by the given parametric equations. Use arrows to show the orientation of the curve corresponding to increasing values of t. (If an interval for t is not specified, assume that −∞ < t < ∞. x = 2ᵗ, y = 2⁻ᵗ; t ≥ 0
Ch. 5 - Complex Numbers, Polar Coordinates and Parametric Equations

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Blitzer 3rd Edition
Ch. 5 - Complex Numbers, Polar Coordinates and Parametric Equations
Problem 39
Blitzer 3rd Edition
Ch. 5 - Complex Numbers, Polar Coordinates and Parametric Equations
Problem 39Chapter 5, Problem 39
In Exercises 33–40, polar coordinates of a point are given. Find the rectangular coordinates of each point. (7.4, 2.5)
Verified step by step guidance1
Recall the relationship between polar coordinates \((r, \theta)\) and rectangular coordinates \((x, y)\), where \(x = r \cos(\theta)\) and \(y = r \sin(\theta)\).
Identify the given polar coordinates: \(r = 7.4\) and \(\theta = 2.5\) radians.
Calculate the \(x\)-coordinate using the formula \(x = 7.4 \times \cos(2.5)\).
Calculate the \(y\)-coordinate using the formula \(y = 7.4 \times \sin(2.5)\).
Express the rectangular coordinates as the ordered pair \((x, y)\) using the values found in the previous steps.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Polar Coordinates
Polar coordinates represent a point in the plane using a distance from the origin (radius r) and an angle (θ) measured from the positive x-axis. The given point (7.4, 2.5) means r = 7.4 and θ = 2.5 radians.
Recommended video:
Intro to Polar Coordinates
Conversion from Polar to Rectangular Coordinates
To convert polar coordinates (r, θ) to rectangular coordinates (x, y), use the formulas x = r cos(θ) and y = r sin(θ). This translates the point from a radius-angle format to Cartesian coordinates on the xy-plane.
Recommended video:
Convert Points from Polar to Rectangular
Trigonometric Functions (Sine and Cosine)
Sine and cosine functions relate an angle in a right triangle to the ratios of its sides. Cosine gives the ratio of the adjacent side to the hypotenuse, and sine gives the ratio of the opposite side to the hypotenuse, essential for coordinate conversion.
Recommended video:
Graph of Sine and Cosine Function
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