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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 6.3.35

Solve each equation (x in radians and θ in degrees) for all exact solutions where appropriate. Round approximate answers in radians to four decimal places and approximate answers in degrees to the nearest tenth. Write answers using the least possible nonnegative angle measures.


√2 sin 3x - 1 = 0

Verified step by step guidance
1
Start by isolating the sine term in the equation: \( \sqrt{2} \sin 3x - 1 = 0 \). Add 1 to both sides to get \( \sqrt{2} \sin 3x = 1 \).
Next, divide both sides by \( \sqrt{2} \) to solve for \( \sin 3x \): \( \sin 3x = \frac{1}{\sqrt{2}} \).
Recall that \( \sin \theta = \frac{1}{\sqrt{2}} \) corresponds to angles where \( \theta = \frac{\pi}{4} + 2k\pi \) or \( \theta = \frac{3\pi}{4} + 2k\pi \) for any integer \( k \). Here, \( \theta = 3x \).
Set up the two equations for \( 3x \): \( 3x = \frac{\pi}{4} + 2k\pi \) and \( 3x = \frac{3\pi}{4} + 2k\pi \), where \( k \) is any integer.
Solve each equation for \( x \) by dividing both sides by 3: \( x = \frac{\pi}{12} + \frac{2k\pi}{3} \) and \( x = \frac{3\pi}{12} + \frac{2k\pi}{3} \). Then, find all solutions within the desired interval, and convert to degrees if needed, rounding as specified.

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Key Concepts

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

Solving Trigonometric Equations

This involves isolating the trigonometric function and finding all angle values that satisfy the equation within a given domain. Solutions often include general forms using periodicity, and exact or approximate values depending on the problem's requirements.
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Angle Measures and Unit Conversion

Understanding the difference between radians and degrees is essential, as well as converting between them. Radians are based on the radius of a circle, while degrees divide a circle into 360 parts. Correct unit usage ensures accurate solutions and proper rounding.
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Reference Angles on the Unit Circle

Using Inverse Trigonometric Functions and Periodicity

Inverse sine (arcsin) helps find principal angle solutions, but because sine is periodic with period 2π (or 360°), all solutions must account for this repetition. Writing solutions with the least nonnegative angle measures requires adjusting for these periodic intervals.
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Introduction to Inverse Trig Functions