/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 27 Solving a Trigonometric Equation... [FREE SOLUTION] | 91Ó°ÊÓ

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Solving a Trigonometric Equation In Exercises \(25-38,\) find all solutions of the equation in the interval \(0,2 \pi ) .\) $$3 \tan ^{3} x=\tan x$$

Short Answer

Expert verified
The solutions to the given trigonometric equation within the interval \(0\) and \(2\pi\) are \(x = 0\), \(x = \pi\), \(x = \arctan(\sqrt{1/3})\), \(x = \pi - \arctan(\sqrt{1/3})\), \(x = \pi + \arctan(\sqrt{1/3})\), \(x = 2\pi - \arctan(\sqrt{1/3})\).

Step by step solution

01

Simplify the equation

The first step would be to simplify the given equation, \(3 \tan ^{3} x = \tan x\). This can be done by dividing both sides by \(\tan x\), which gives: \(3\tan ^{2} x = 1\) . This operation is possible based on the assumption that \(\tan x\neq 0\) or \(x\neq k\pi\), where \(k\) is an integer.
02

Solve for \(x\)

The next step involves solving for \(x\). Here, the equation \(3 \tan ^{2} x = 1\) becomes \(\tan ^{2} x = 1/3\). By taking square roots on both sides, obtain \(\tan x = \pm\sqrt{1/3}\). Given that \(\tan\pi/4 = 1\) and it is decreasing function in \((\pi/2, 3\pi/2)\) and increasing function in \((k\pi,(k+1)\pi)\) where \(k\) is an integer excluding \((k\pi/2, (k+1)\pi/2)\), the solutions in \((0, \pi)\) will be \(x_1 = \arctan(\sqrt{1/3})\), \(x_2 = \pi - \arctan(\sqrt{1/3})\). The solution \((\pi, 2\pi)\) will be \(x_3 = \pi + \arctan(\sqrt{1/3})\), \(x_4 = 2\pi - \arctan(\sqrt{1/3})\).
03

Review the solutions

Lastly, we need to include the solutions when \(\tan x = 0\). In the range \(0\) to \(2\pi\), the tangent function is zero at \(x = 0\) and \(x = \pi\). Therefore, all solutions are found by adding these solutions to our previously found solutions.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Solving Equations
When it comes to solving equations, the key is breaking down the process into manageable steps. For trigonometric equations like the one in the problem, the aim is to isolate the term involving the trigonometric function. In the equation \(3 \tan^{3} x = \tan x\), the first smart move is simplifying by dividing both sides by \(\tan x\). This is done under the condition that \(\tan x eq 0\), to avoid division by zero.

This step reduces the equation to \(3 \tan^{2} x = 1\). Solving the simplified form involves algebraic manipulation or using inverse functions, leading us to find the values for \(x\). This procedure is a common technique for handling various trigonometric equations, helping break complex problems into simpler parts.
Tangent Function
The tangent function, denoted as \(\tan x\), is a fundamental trigonometric function with periodic properties. Tan is known for its unique behavior across its domain. It repeats its pattern every \(\pi\) radians, illustrating its periodic nature.

For any angle \(x\), \(\tan x\) can take on any real number value, making it different from sine and cosine. This characteristic is pivotal when resolving equations like \(3 \tan^{3} x = \tan x\). The function’s undefined points occur where the cosine is zero (e.g., \(\frac{\pi}{2}, \frac{3\pi}{2}\), etc.), leading to asymptotes in its graph.

Such properties are crucial when determining solutions to trigonometric equations, especially when understanding where the function increases or decreases, further aiding in pinpointing solution intervals.
Interval Solutions
In trigonometric equations, finding solutions within a specified interval is crucial. The given interval \( (0, 2\pi) \) represents one complete cycle of the unit circle. This range helps us determine relevant solutions that match the periodic nature of trigonometric functions.

By solving \(3 \tan^{2} x = 1\), we use the inverse tangent function, identifying where the function equals \(\sqrt{1/3}\) and \(-\sqrt{1/3}\). Specifically, solutions in \((0, \pi)\) include \(x_1 = \arctan(\sqrt{1/3})\) and \(x_2 = \pi - \arctan(\sqrt{1/3})\). Equally, in \((\pi, 2\pi)\), solutions are \(x_3 = \pi + \arctan(\sqrt{1/3})\) and \(x_4 = 2\pi - \arctan(\sqrt{1/3})\).

This technique ensures that solutions are logically extracted from intervals where the tangent function behaves predictably, aiding in clear and accurate trigonometric problem-solving.
Trigonometric Identities
Trigonometric identities are essential tools for simplifying and solving equations. They provide relationships between different trigonometric functions, allowing problems to be expressed and solved in various ways.

In this particular exercise, the identity \(\tan(x) = \frac{\sin(x)}{\cos(x)}\) helps us comprehend how the function behaves over its interval. These identities are used in solving equations by transforming and simplifying expressions, offering alternative views and solutions, especially when working with exponential relations or higher powers, as seen with \(3 \tan^{3} x = \tan x\).

By employing identities, simplifying intricate relations becomes achievable, making the mathematics behind trigonometric equations both accessible and solvable.

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Most popular questions from this chapter

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