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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 6.2.59

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.
5 + 5 tan² θ = 6 sec θ

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Start by rewriting the given equation: \(5 + 5 \tan^{2} \theta = 6 \sec \theta\).
Recall the Pythagorean identity relating tangent and secant: \(1 + \tan^{2} \theta = \sec^{2} \theta\). Use this to express \(\tan^{2} \theta\) in terms of \(\sec^{2} \theta\) as \(\tan^{2} \theta = \sec^{2} \theta - 1\).
Substitute \(\tan^{2} \theta = \sec^{2} \theta - 1\) into the original equation to get \(5 + 5(\sec^{2} \theta - 1) = 6 \sec \theta\).
Simplify the equation to form a quadratic in \(\sec \theta\): \(5 + 5 \sec^{2} \theta - 5 = 6 \sec \theta\), which reduces to \(5 \sec^{2} \theta = 6 \sec \theta\).
Rewrite the equation as \(5 \sec^{2} \theta - 6 \sec \theta = 0\), factor it, and solve for \(\sec \theta\). Then, find the corresponding values of \(\theta\) by considering the definition \(\sec \theta = \frac{1}{\cos \theta}\) and solving for \(\theta\) in the specified domain, ensuring to express solutions in the least possible nonnegative angle measures.

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