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Ch. 6 - Inverse Circular Functions and Trigonometric Equations
Lial - Trigonometry 12th Edition
Lial12th EditionTrigonometryISBN: 9780136552161Not the one you use?Change textbook
Chapter 7, Problem 6.RE.41

Solve each equation over the interval [0, 2π). Write solutions as exact values or to four decimal places, as appropriate.
tan² 2x -1 = 0

Verified step by step guidance
1
Start with the given equation: \(\tan^{2} 2x - 1 = 0\).
Rewrite the equation to isolate the squared tangent term: \(\tan^{2} 2x = 1\).
Take the square root of both sides, remembering to consider both positive and negative roots: \(\tan 2x = \pm 1\).
Solve for \$2x\( by finding all angles where \(\tan \theta = 1\) and \(\tan \theta = -1\) within one full period of tangent, which is \(\pi\). So, \(2x = \frac{\pi}{4} + k\pi\) and \(2x = \frac{3\pi}{4} + k\pi\), where \)k$ is any integer.
Divide all solutions by 2 to solve for \(x\), then find all values of \(x\) within the interval \([0, 2\pi)\) by choosing appropriate integer values of \(k\).

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Solving Trigonometric Equations

Solving trigonometric equations involves finding all angle values within a specified interval that satisfy the given equation. This often requires algebraic manipulation and applying inverse trigonometric functions, while considering the periodic nature of trig functions to find all valid solutions.
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Properties of the Tangent Function

The tangent function, tan(θ), is periodic with period π and is defined as sin(θ)/cos(θ). Understanding its behavior, including where it is positive or negative and its undefined points, is essential for solving equations involving tan²(θ) and for determining all solutions within a given interval.
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Using Double-Angle Identities

Double-angle identities express trigonometric functions of 2x in terms of x, such as tan(2x) = 2tan(x)/(1 - tan²(x)). Recognizing and applying these identities helps simplify equations involving multiple angles, enabling easier solution of equations like tan²(2x) - 1 = 0.
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