Skip to main content
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 6.3.43

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.


1 - sin x = cos 2x

Guida verificata passo dopo passo
1
Rewrite the given equation: \(1 - \sin x = \cos 2x\).
Recall the double-angle identity for cosine: \(\cos 2x = 1 - 2\sin^2 x\). Substitute this into the equation to get \(1 - \sin x = 1 - 2\sin^2 x\).
Simplify the equation by subtracting 1 from both sides: \(-\sin x = -2\sin^2 x\). Then multiply both sides by -1 to get \(\sin x = 2\sin^2 x\).
Rewrite the equation as \(2\sin^2 x - \sin x = 0\) and factor it: \(\sin x (2\sin x - 1) = 0\).
Set each factor equal to zero and solve for \(x\): 1) \(\sin x = 0\) 2) \(2\sin x - 1 = 0 \Rightarrow \sin x = \frac{1}{2}\). Find all solutions for \(x\) in radians within the specified domain, then convert to degrees if needed, and express answers as the least possible nonnegative angles.

Risposta video verificata per un problema simile:

Questa soluzione video è stata consigliata dai nostri tutor come utile per risolvere questo problema.

Concetti chiave

Ecco i concetti essenziali che devi comprendere per rispondere correttamente alla domanda.

Trigonometric Identities

Trigonometric identities are equations involving trigonometric functions that hold true for all values within their domains. For this problem, the double-angle identity for cosine, cos 2x = 1 - 2sin²x or cos 2x = 2cos²x - 1, is essential to rewrite and simplify the equation for easier solving.
Video consigliato:
Percorso guidato
5:32
Fundamental Trigonometric Identities

Solving Trigonometric Equations

Solving trigonometric equations involves isolating the trigonometric function and finding all angle solutions within a given domain. This includes considering the periodic nature of sine and cosine functions and expressing solutions using general formulas that account for all possible angles.
Video consigliato:
Percorso guidato
4:34
How to Solve Linear Trigonometric Equations

Angle Measurement and Conversion

Understanding angle measurements in radians and degrees is crucial, as the problem requires solutions in both units. Converting between radians and degrees and expressing answers within the least nonnegative angle measure ensures clarity and correctness in the final solutions.
Video consigliato:
Percorso guidato
5:31
Reference Angles on the Unit Circle