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Ch. 2 - Graphs of the Trigonometric Functions; Inverse Trigonometric Functions
Blitzer - Trigonometry 3rd Edition
Blitzer3rd EditionTrigonometryISBN: 9780137316601당신이 사용하는 게 아니라요?교과서 변경
2장, 문제 23

In Exercises 17–24, graph two periods of the given cotangent function. y = 3 cot(x + π/2)

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1
Recall the general form of the cotangent function: \(y = A \cot(Bx + C)\), where \(A\) affects the amplitude (vertical stretch), \(B\) affects the period, and \(C\) is the phase shift.
Identify the parameters in the given function \(y = 3 \cot(x + \frac{\pi}{2})\): here, \(A = 3\), \(B = 1\), and \(C = \frac{\pi}{2}\).
Calculate the period of the cotangent function using the formula \(\text{Period} = \frac{\pi}{|B|}\). Since \(B = 1\), the period is \(\pi\).
Determine the phase shift by solving \(Bx + C = 0\), which gives \(x = -\frac{C}{B} = -\frac{\pi}{2}\). This means the graph is shifted to the left by \(\frac{\pi}{2}\).
To graph two periods, plot the cotangent function starting from \(x = -\frac{\pi}{2}\) and extend the graph over an interval of length \(2 \times \pi = 2\pi\). Mark key points such as zeros, vertical asymptotes, and the shape of the curve scaled by the amplitude 3.

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주요 개념

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

Cotangent Function and Its Properties

The cotangent function, cot(x), is the reciprocal of the tangent function and is defined as cos(x)/sin(x). It has vertical asymptotes where sin(x) = 0, i.e., at integer multiples of π, and its period is π. Understanding its shape and behavior is essential for graphing.
추천 영상:
5:37
Introduction to Cotangent Graph

Phase Shift in Trigonometric Functions

A phase shift occurs when the input variable x is replaced by (x + c), shifting the graph horizontally. For y = cot(x + π/2), the graph shifts left by π/2 units. Recognizing this shift helps in correctly positioning the graph on the x-axis.
추천 영상:
6:31
Phase Shifts

Amplitude and Vertical Stretch

The coefficient 3 in y = 3 cot(x + π/2) vertically stretches the cotangent graph by a factor of 3. While cotangent has no maximum or minimum values, this stretch affects the steepness of the curve, making it rise and fall more sharply.
추천 영상:
6:02
Stretches and Shrinks of Functions