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Ch. 5 - Complex Numbers, Polar Coordinates and Parametric Equations
Blitzer - Trigonometry 3rd Edition
Blitzer3rd EditionTrigonometryISBN: 9780137316601당신이 사용하는 게 아니라요?교과서 변경
5장, 문제 27

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 = 2 sin t, y = 2 cos t; 0 ≤ t < 2π

검증된 단계별 안내
1
Identify the given parametric equations: \(x = 2 \sin t\) and \(y = 2 \cos t\), with the parameter \(t\) in the interval \(0 \leq t < 2\pi\).
Recall the Pythagorean identity: \(\sin^2 t + \cos^2 t = 1\). This identity will help us eliminate the parameter \(t\) by expressing \(\sin t\) and \(\cos t\) in terms of \(x\) and \(y\).
Express \(\sin t\) and \(\cos t\) from the parametric equations: \(\sin t = \frac{x}{2}\) and \(\cos t = \frac{y}{2}\).
Substitute these expressions into the Pythagorean identity to get the rectangular equation: \(\left(\frac{x}{2}\right)^2 + \left(\frac{y}{2}\right)^2 = 1\).
Simplify the equation to the standard form of a circle: \(\frac{x^2}{4} + \frac{y^2}{4} = 1\). This represents a circle centered at the origin with radius 2. To sketch the curve, draw this circle and use the parameter interval to determine the orientation, noting that as \(t\) increases from \(0\) to \(2\pi\), the point moves clockwise because \(x = 2 \sin t\) and \(y = 2 \cos t\).

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주요 개념

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

Parametric Equations

Parametric equations express the coordinates of points on a curve as functions of a parameter, often denoted as t. Instead of y as a function of x, both x and y depend on t, allowing the description of more complex curves and motions. Understanding how to manipulate these equations is key to analyzing the curve's shape and behavior.
추천 영상:
08:02
Parameterizing Equations

Eliminating the Parameter

Eliminating the parameter involves rewriting the parametric equations to form a single equation in x and y, removing t. This is done by expressing t from one equation and substituting into the other or using trigonometric identities. This step converts the parametric form into a rectangular (Cartesian) equation, simplifying graphing and analysis.
추천 영상:
05:59
Eliminating the Parameter

Orientation and Sketching of Parametric Curves

Orientation refers to the direction in which the curve is traced as the parameter t increases. When sketching, arrows indicate this direction, helping to understand the curve's dynamic behavior. Recognizing the interval of t and how x and y change with t is essential for accurate graphing and interpretation.
추천 영상:
04:47
Introduction to Parametric Equations