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Ch. 6 - Inverse Circular Functions and Trigonometric Equations
Lial - Trigonometry 12th Edition
Lial12th EditionTrigonometryISBN: 9780136552161, 9780135440780, 9780136881117, 9780135440827, 9780135924891Non è quello che usi tu?Cambia libro di testo
Capitolo 7, Problema 29

Solve each equation over the interval [0°, 360°). Write solutions as exact values or to the nearest tenth, as appropriate.
2sin θ ―1 = csc θ

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Rewrite the given equation \(2\sin \theta - 1 = \csc \theta\) by expressing \(\csc \theta\) in terms of \(\sin \theta\). Recall that \(\csc \theta = \frac{1}{\sin \theta}\), so the equation becomes \(2\sin \theta - 1 = \frac{1}{\sin \theta}\).
Multiply both sides of the equation by \(\sin \theta\) to eliminate the fraction, keeping in mind that \(\sin \theta \neq 0\) to avoid division by zero. This gives \(2\sin^2 \theta - \sin \theta = 1\).
Rearrange the equation to standard quadratic form in terms of \(\sin \theta\): \(2\sin^2 \theta - \sin \theta - 1 = 0\).
Use the quadratic formula to solve for \(\sin \theta\). Recall the quadratic formula is \(x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\), where \(a=2\), \(b=-1\), and \(c=-1\). Substitute these values to find the possible values of \(\sin \theta\).
For each solution of \(\sin \theta\), determine the corresponding angles \(\theta\) in the interval \([0^\circ, 360^\circ)\) by using the inverse sine function and considering the sine function's positive and negative values in different quadrants.

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Solving equations like 2sin θ - 1 = csc θ involves algebraic manipulation and applying identities. After rewriting, isolate the trigonometric function and find all solutions within the given interval, considering the domain restrictions.
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Interval and Solution Constraints

The problem restricts θ to [0°, 360°), so solutions must be found within one full rotation of the unit circle. Understanding how to find all valid angles in this interval ensures complete and accurate answers.
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