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Ch. 6 - Inverse Circular Functions and Trigonometric Equations
Lial - Trigonometry 12th Edition
Lial12th EditionTrigonometryISBN: 9780136552161당신이 사용하는 게 아니라요?교과서 변경
7장, 문제 23

Solve each equation for x, where x is restricted to the given interval.
y = √2 + 3 sec 2x, for x in [0, π/4) ⋃ (π/4, π/2]

검증된 단계별 안내
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Rewrite the given equation: \(y = \sqrt{2} + 3 \sec 2x\). Our goal is to solve for \(x\) in the interval \([0, \frac{\pi}{4}) \cup (\frac{\pi}{4}, \frac{\pi}{2}]\).
Isolate the \(\sec 2x\) term by subtracting \(\sqrt{2}\) from both sides: \(y - \sqrt{2} = 3 \sec 2x\). Then divide both sides by 3 to get \(\sec 2x = \frac{y - \sqrt{2}}{3}\).
Recall that \(\sec \theta = \frac{1}{\cos \theta}\). So, rewrite the equation as \(\frac{1}{\cos 2x} = \frac{y - \sqrt{2}}{3}\), which implies \(\cos 2x = \frac{3}{y - \sqrt{2}}\).
Solve for \$2x\( by taking the inverse cosine (arccos) of both sides: \(2x = \arccos \left( \frac{3}{y - \sqrt{2}} \right)\). Remember that cosine is positive in the first and fourth quadrants, so consider all possible solutions for \)2x$ within the domain.
Finally, divide by 2 to solve for \(x\): \(x = \frac{1}{2} \arccos \left( \frac{3}{y - \sqrt{2}} \right)\). Check which solutions fall within the given interval \([0, \frac{\pi}{4}) \cup (\frac{\pi}{4}, \frac{\pi}{2}]\) and exclude any values where \(\sec 2x\) is undefined (such as at \(x = \frac{\pi}{4}\)).

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주요 개념

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