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Ch.12 - Parametric and Polar Curves
Briggs - Calculus: Early Transcendentals 3rd Edition
Briggs3rd EditionCalculus: Early TranscendentalsISBN: 9780136847243당신이 사용하는 게 아니라요?교과서 변경
12장, 문제 12.2.106d

(Use of Tech) Finger curves: r = f(θ) = cos(aᶿ) - 1.5, where a = (1 + 12π)^(1/(2π)) ≈ 1.78933
d. Plot the curve with various values of k. How many fingers can you produce?

검증된 단계별 안내
1
Understand the given polar curve equation: \(r = f(\theta) = \cos(a\theta) - 1.5\), where \(a = (1 + 12\pi)^{\frac{1}{2\pi}}\). This defines the radius \(r\) as a function of the angle \(\theta\).
Recognize that the parameter \(a\) controls the frequency of the cosine function inside the polar equation, which affects the number of 'fingers' or lobes in the plot.
To explore how the number of fingers changes, vary the parameter \(k\) in the expression for \(a\), for example by replacing \(a\) with \(k\) in the function \(r = \cos(k\theta) - 1.5\) and plotting for different values of \(k\).
For each chosen value of \(k\), plot the curve in polar coordinates over a full rotation, typically \(\theta\) from \(0\) to \(2\pi\), to observe the shape and count the number of distinct lobes or fingers formed.
Analyze the plots to determine the relationship between \(k\) and the number of fingers: generally, the number of fingers corresponds to the integer part of \(k\) or related to the frequency of the cosine term, so by increasing \(k\), you can produce more fingers.

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Polar Coordinates and Curves

Polar coordinates represent points using a radius and an angle (r, θ), allowing curves to be defined as functions of θ. Understanding how to interpret and plot r = f(θ) is essential for visualizing shapes like finger curves, where the radius changes with the angle.
추천 영상:
05:32
Intro to Polar Coordinates

Parameter Influence on Curve Shape

Parameters within the function, such as 'a' in r = cos(aθ) - 1.5, control the frequency and number of oscillations in the curve. Varying these parameters changes the number of 'fingers' or lobes in the plot, so analyzing their effect helps predict and count the features formed.
추천 영상:
05:59
Eliminating the Parameter

Use of Technology for Plotting

Graphing software or calculators can plot complex polar functions efficiently, allowing exploration of how different parameter values affect the curve. Using technology helps visualize the number of fingers produced and understand the behavior of the function dynamically.
추천 영상:
04:48
Finding Volume Using Disks