In Exercises 121โ126, solve each equation on the interval [0, 2๐ ). 10 cosยฒ x + 3 sin x - 9 = 0
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- 0. Review of College Algebra4h 45m
- 1. Measuring Angles40m
- 2. Trigonometric Functions on Right Triangles2h 5m
- 3. Unit Circle1h 19m
- 4. Graphing Trigonometric Functions1h 19m
- 5. Inverse Trigonometric Functions and Basic Trigonometric Equations1h 41m
- 6. Trigonometric Identities and More Equations2h 34m
- 7. Non-Right Triangles1h 38m
- 8. Vectors2h 25m
- 9. Polar Equations2h 5m
- 10. Parametric Equations1h 6m
- 11. Graphing Complex Numbers1h 7m
5. Inverse Trigonometric Functions and Basic Trigonometric Equations
Linear Trigonometric Equations
Problem 3.RE.62
Textbook Question
In Exercises 54โ67, solve each equation on the interval [0, 2๐ ). Use exact values where possible or give approximate solutions correct to four decimal places. sin 2x = โ 3 sin x
Verified step by step guidance1
Start by rewriting the given equation: \(\sin 2x = \sqrt{3} \sin x\).
Use the double-angle identity for sine: \(\sin 2x = 2 \sin x \cos x\). Substitute this into the equation to get \(2 \sin x \cos x = \sqrt{3} \sin x\).
Bring all terms to one side: \(2 \sin x \cos x - \sqrt{3} \sin x = 0\). Factor out \(\sin x\): \(\sin x (2 \cos x - \sqrt{3}) = 0\).
Set each factor equal to zero and solve separately:
1) \(\sin x = 0\)
2) \(2 \cos x - \sqrt{3} = 0\).
For \(\sin x = 0\), find all \(x\) in \([0, 2\pi)\) where sine is zero. For \(2 \cos x - \sqrt{3} = 0\), solve for \(\cos x = \frac{\sqrt{3}}{2}\) and find all \(x\) in \([0, 2\pi)\) that satisfy this.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Double-Angle Identity for Sine
The double-angle identity expresses sin(2x) as 2 sin(x) cos(x). This allows rewriting the equation sin 2x = โ3 sin x into a form involving sin(x) and cos(x), facilitating algebraic manipulation and solution finding.
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Solving Trigonometric Equations
Solving trigonometric equations involves isolating the trigonometric function and finding all angle solutions within the given interval. It often requires factoring, using identities, and considering the periodic nature of sine and cosine functions.
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How to Solve Linear Trigonometric Equations
Interval Restriction and Exact Values
Solutions must be found within the interval [0, 2ฯ), meaning all valid angles between 0 and 2ฯ are considered. Using exact values (like ฯ/3, ฯ/6) is preferred, but approximate decimal values to four decimal places are acceptable when exact forms are complex.
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