Answered

Find all solutions of the equation in the interval [tex]$[0, 2\pi)$[/tex].

[tex]\[ (\sec x - \sqrt{2})(\sin x - 4) = 0 \][/tex]

Write your answer in radians in terms of [tex]$\pi$[/tex].
If there is more than one solution, separate them with commas.

[tex]\[ x = \boxed{\quad} \][/tex]



Answer :

To solve the equation [tex]\((\sec x - \sqrt{2})(\sin x - 4) = 0\)[/tex] in the interval [tex]\([0, 2\pi)\)[/tex], we need to consider the solutions of each factor set to zero individually.

#### Step 1: Solve [tex]\(\sec x - \sqrt{2} = 0\)[/tex]

[tex]\[ \sec x - \sqrt{2} = 0 \implies \sec x = \sqrt{2} \][/tex]

Recall that [tex]\(\sec x = \frac{1}{\cos x}\)[/tex], so we have:

[tex]\[ \frac{1}{\cos x} = \sqrt{2} \implies \cos x = \frac{1}{\sqrt{2}} = \frac{\sqrt{2}}{2} \][/tex]

The cosine function [tex]\(\cos x = \frac{\sqrt{2}}{2}\)[/tex] has solutions at:

[tex]\[ x = \frac{\pi}{4} + 2k\pi \quad \text{and} \quad x = -\frac{\pi}{4} + 2k\pi \quad \text{for} \quad k \in \mathbb{Z} \][/tex]

To find solutions within the interval [tex]\([0, 2\pi)\)[/tex], we consider:

[tex]\[ x = \frac{\pi}{4}, \quad x = \frac{7\pi}{4} \][/tex]

However, since [tex]\(\frac{7\pi}{4} - 2\pi\)[/tex] results in an angle outside the interval [tex]\([0, 2\pi)\)[/tex], the valid solution for the interval is:

[tex]\[ x = \frac{\pi}{4} \][/tex]

#### Step 2: Solve [tex]\(\sin x - 4 = 0\)[/tex]

[tex]\[ \sin x - 4 = 0 \implies \sin x = 4 \][/tex]

The sine function, [tex]\(\sin x\)[/tex], ranges from [tex]\(-1\)[/tex] to [tex]\(1\)[/tex]. Since [tex]\(4\)[/tex] lies outside this range, there are no valid solutions for this equation.

#### Step 3: Combine the solutions

The only valid solution for the original equation in the interval [tex]\([0, 2\pi)\)[/tex] is:

[tex]\[ x = \frac{\pi}{4} \][/tex]

Therefore, the solution is:

[tex]\[ x = \frac{\pi}{4} \][/tex]