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29. \( \sec ^{2} x-\sec x=2 \) 30. \( \sec x \csc x=2 \csc x \) 31. \( 2 \sin x+\csc x=0 \)

Ask by Montgomery Adkins. in the United States
Jan 21,2025

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Answer

Solutions: 1. **Problem 29:** \[ x = \frac{\pi}{3} + 2\pi k, \quad \frac{5\pi}{3} + 2\pi k, \quad \text{or} \quad \pi + 2\pi k \quad \text{where } k \text{ is an integer} \] 2. **Problem 30:** \[ x = \frac{\pi}{3} + 2\pi k \quad \text{and} \quad x = \frac{5\pi}{3} + 2\pi k \quad \text{where } k \text{ is an integer} \] 3. **Problem 31:** No real solutions exist.

Solution

Certainly! Let's solve each of the given trigonometric equations step by step. --- ## Problem 29 **Equation:** \[ \sec^{2} x - \sec x = 2 \] **Solution:** 1. **Substitute \( \sec x \) with a variable:** Let \( y = \sec x \). The equation becomes: \[ y^2 - y = 2 \] 2. **Rearrange the equation:** \[ y^2 - y - 2 = 0 \] 3. **Solve the quadratic equation:** \[ y = \frac{1 \pm \sqrt{1 + 8}}{2} = \frac{1 \pm 3}{2} \] So, \( y = 2 \) or \( y = -1 \). 4. **Find \( x \) for each case:** - **Case 1:** \( \sec x = 2 \) \[ \cos x = \frac{1}{2} \] The solutions for \( \cos x = \frac{1}{2} \) are: \[ x = \frac{\pi}{3} + 2\pi k \quad \text{and} \quad x = \frac{5\pi}{3} + 2\pi k \quad \text{where } k \text{ is an integer} \] - **Case 2:** \( \sec x = -1 \) \[ \cos x = -1 \] The solution for \( \cos x = -1 \) is: \[ x = \pi + 2\pi k \quad \text{where } k \text{ is an integer} \] 5. **General Solution:** \[ x = \frac{\pi}{3} + 2\pi k, \quad \frac{5\pi}{3} + 2\pi k, \quad \text{or} \quad \pi + 2\pi k \quad \text{where } k \text{ is an integer} \] --- ## Problem 30 **Equation:** \[ \sec x \csc x = 2 \csc x \] **Solution:** 1. **Assume \( \csc x \neq 0 \):** Since \( \csc x = \frac{1}{\sin x} \), \( \sin x \neq 0 \). 2. **Divide both sides by \( \csc x \):** \[ \sec x = 2 \] 3. **Solve for \( x \):** \[ \sec x = 2 \implies \cos x = \frac{1}{2} \] 4. **Find \( x \):** The solutions for \( \cos x = \frac{1}{2} \) are: \[ x = \frac{\pi}{3} + 2\pi k \quad \text{and} \quad x = \frac{5\pi}{3} + 2\pi k \quad \text{where } k \text{ is an integer} \] --- ## Problem 31 **Equation:** \[ 2 \sin x + \csc x = 0 \] **Solution:** 1. **Express \( \csc x \) in terms of \( \sin x \):** \[ 2 \sin x + \frac{1}{\sin x} = 0 \] 2. **Multiply both sides by \( \sin x \) (assuming \( \sin x \neq 0 \)):** \[ 2 \sin^2 x + 1 = 0 \] 3. **Rearrange the equation:** \[ 2 \sin^2 x = -1 \implies \sin^2 x = -\frac{1}{2} \] 4. **Analyze the equation:** \( \sin^2 x \) is always non-negative for real numbers, but the equation \( \sin^2 x = -\frac{1}{2} \) implies that \( \sin^2 x \) is negative, which is impossible. 5. **Conclusion:** There are **no real solutions** to the equation \( 2 \sin x + \csc x = 0 \). --- If you have any further questions or need additional clarification on these problems, feel free to ask!

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Beyond the Answer

For the equation \( \sec^{2} x - \sec x = 2 \), you can start by letting \( y = \sec x \). This transforms the equation into a quadratic form: \( y^{2} - y - 2 = 0 \). By factoring, you get \( (y-2)(y+1) = 0 \), leading to solutions for \( y = 2 \) (yielding \( \sec x = 2 \)) and \( y = -1 \) (which doesn't yield valid angles). In the second equation \( \sec x \csc x = 2 \csc x \), you can simplify by dividing both sides by \( \csc x \) (assuming \( \csc x \neq 0 \)), giving \( \sec x = 2 \). This again leads to the angle where \( \sec x = 2 \), which means \( x = \frac{\pi}{3} + 2n\pi \) or \( x = -\frac{\pi}{3} + 2n\pi \), where \( n \) is any integer. For \( 2 \sin x + \csc x = 0 \), replace \( \csc x \) with \( \frac{1}{\sin x} \). The equation rearranges to \( 2 \sin^2 x + 1 = 0 \). Since there are no real solutions for this scenario (as \( \sin^2 x \) can't be negative), you would conclude that this equation doesn't have any valid solutions in the real number domain!

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