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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 39

Solve each equation for exact solutions.
sin⁻¹ x - tan⁻¹ 1 = -π/4

Verified step by step guidance
1
Recognize that the equation is given as \(\sin^{-1} x - \tan^{-1} 1 = -\frac{\pi}{4}\), where \(\sin^{-1} x\) and \(\tan^{-1} 1\) are inverse trigonometric functions (arcsine and arctangent respectively).
Recall the exact value of \(\tan^{-1} 1\). Since \(\tan \frac{\pi}{4} = 1\), it follows that \(\tan^{-1} 1 = \frac{\pi}{4}\).
Substitute \(\tan^{-1} 1 = \frac{\pi}{4}\) into the equation to get \(\sin^{-1} x - \frac{\pi}{4} = -\frac{\pi}{4}\).
Add \(\frac{\pi}{4}\) to both sides to isolate \(\sin^{-1} x\): \(\sin^{-1} x = -\frac{\pi}{4} + \frac{\pi}{4} = 0\).
Use the definition of the inverse sine function to solve for \(x\): since \(\sin^{-1} x = 0\), then \(x = \sin 0\). Recall that \(\sin 0 = 0\), so \(x = 0\).

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Key Concepts

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

Inverse Trigonometric Functions

Inverse trigonometric functions, such as sin⁻¹ (arcsin) and tan⁻¹ (arctan), return the angle whose sine or tangent is a given value. Understanding their domains and ranges is essential for solving equations involving these functions and finding exact angle measures.
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Properties of the Arctangent Function

The arctangent function, tan⁻¹(x), outputs angles in the interval (-π/2, π/2). Knowing specific values, like tan⁻¹(1) = π/4, helps simplify expressions and solve equations involving inverse tangent terms.
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Solving Trigonometric Equations for Exact Values

Solving trigonometric equations involves isolating the inverse trig functions and using known exact values or identities. This process often requires manipulating the equation to express one inverse function in terms of another and applying angle addition or subtraction formulas.
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