Find all solutions to [tex]$2 \sin (\theta)=-\sqrt{2}$[/tex] on the interval [tex]$0 \leq \theta \ \textless \ 2 \pi$[/tex].

[tex]\theta=[/tex]

Give your answers as exact values, separated by commas.



Answer :

To find all solutions to the equation [tex]\(2 \sin (\theta) = -\sqrt{2}\)[/tex] within the interval [tex]\(0 \leq \theta < 2\pi\)[/tex], follow these steps:

1. Isolate the sine function:
[tex]\[ 2 \sin (\theta) = -\sqrt{2} \][/tex]
Divide both sides by 2 to get:
[tex]\[ \sin (\theta) = -\frac{\sqrt{2}}{2} \][/tex]

2. Determine the reference angle:
We know that for [tex]\(\sin (\alpha) = -\frac{\sqrt{2}}{2}\)[/tex], the reference angle [tex]\(\alpha\)[/tex] where [tex]\(\sin (\alpha) = \frac{\sqrt{2}}{2}\)[/tex] is [tex]\(\frac{\pi}{4}\)[/tex].

3. Find the general solutions:
Since the sine function is negative in the third and fourth quadrants, the angles corresponding to [tex]\(\sin (\theta) = -\frac{\sqrt{2}}{2}\)[/tex] within one period [tex]\([0, 2\pi)\)[/tex] are:
[tex]\[ \theta = \pi + \frac{\pi}{4} \quad \text{and} \quad \theta = 2\pi - \frac{\pi}{4} \][/tex]

4. Calculate the exact values:
[tex]\[ \theta = \pi + \frac{\pi}{4} = \frac{4\pi}{4} + \frac{\pi}{4} = \frac{5\pi}{4} \][/tex]
[tex]\[ \theta = 2\pi - \frac{\pi}{4} = \frac{8\pi}{4} - \frac{\pi}{4} = \frac{7\pi}{4} \][/tex]

5. List the solutions within the given interval:
The solutions to [tex]\(2 \sin (\theta) = -\sqrt{2}\)[/tex] on the interval [tex]\(0 \leq \theta < 2\pi\)[/tex] are:
[tex]\[ \theta = \boxed{\frac{5\pi}{4}, \frac{7\pi}{4}} \][/tex]