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Ch. 1 - Trigonometric Functions
Lial - Trigonometry 12th Edition
Lial12th EditionTrigonometryISBN: 9780136552161, 9780135440780, 9780136881117, 9780135440827, 9780135924891Non è quello che usi tu?Cambia libro di testo
Capitolo 2, Problema 108

Concept Check Find a solution for each equation. sec(2θ + 6°) cos(5θ + 3°) = 1

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1
Recall the definition of secant: \(\sec x = \frac{1}{\cos x}\). Rewrite the equation \(\sec(2\theta + 6^\circ) \cos(5\theta + 3^\circ) = 1\) as \(\frac{1}{\cos(2\theta + 6^\circ)} \cdot \cos(5\theta + 3^\circ) = 1\).
Multiply both sides of the equation by \(\cos(2\theta + 6^\circ)\) to eliminate the fraction, giving \(\cos(5\theta + 3^\circ) = \cos(2\theta + 6^\circ)\).
Use the cosine equation property: if \(\cos A = \cos B\), then \(A = B + 360^\circ k\) or \(A = -B + 360^\circ k\), where \(k\) is any integer.
Set up the two equations based on the property: 1) \(5\theta + 3^\circ = 2\theta + 6^\circ + 360^\circ k\) 2) \(5\theta + 3^\circ = - (2\theta + 6^\circ) + 360^\circ k\)
Solve each linear equation for \(\theta\) by isolating \(\theta\) and expressing the general solution in terms of \(k\).

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