Questions: Determine a general formula (or formulas) for the solutions to the following equation. Then, determine the specific solutions (if any) on the interval [0,2 pi ).
cos theta = 1/sqrt(2)
Describe in the most concise way possible the general solution to the given equation, where k is any integer. Select the correct choice below and fill in all the answer boxes within your choice. (Simplify your answers. Type any angle measures in radians. Use the smallest non-negative angle possible when describing the general form of each angle. Use ascending order, entering the expression based on the smallest angle first. Type exact answers, using pi as needed. Use integers or fractions for any numbers in the expressions.)
A. theta = + k
B. theta = pi/3 + 2 pi k or theta = 5 pi/3 + 2 pi k
C. theta = + k or theta = + k or theta = + k
D. theta = + k or theta = + k or theta = k or theta = + k
E. There is no solution.
Transcript text: Determine a general formula (or formulas) for the solutions to the following equation. Then, determine the specific solutions (if any) on the interval $[0,2 \pi$ ).
\[
\cos \theta=\frac{1}{\sqrt{2}}
\]
Describe in the most concise way possible the general solution to the given equation, where $k$ is any integer. Select the correct choice below and fill in all the answer boxes within your choice.
(Simplify your answers. Type any angle measures in radians. Use the smallest non-negative angle possible when describing the general form of each angle. Use ascending order, entering the expression based on the smallest angle first. Type exact answers, using $\pi$ as needed. Use integers or fractions for any numbers in the expressions.)
A. $\theta=$ $\square$ $+$ $\square$ k
B. $\theta=\frac{\pi}{3}+2 \pi k$ or $\theta=\frac{5 \pi}{3}+2 \pi k$
C. $\theta=\square+\square \mathrm{k}$ or $\theta=\square+\square \mathrm{k}$ or $\theta=\square+\square \mathrm{k}$
D. $\theta=$ $\square$ $+$ $\square$ k or $\theta=\square+\square \mathrm{k}$ or $\theta=$ $\square$ k or $\theta=$ $\square$ $+$ $\square$ k
E. There is no solution.
1
Solution
Solution Steps
To solve the equation \(\cos \theta = \frac{1}{\sqrt{2}}\), we recognize that this corresponds to the angles where the cosine value is \(\frac{1}{\sqrt{2}}\), which are \(\theta = \frac{\pi}{4}\) and \(\theta = \frac{7\pi}{4}\) within the interval \([0, 2\pi]\). The general solution for \(\cos \theta = \frac{1}{\sqrt{2}}\) is given by \(\theta = \frac{\pi}{4} + 2\pi k\) or \(\theta = \frac{7\pi}{4} + 2\pi k\), where \(k\) is any integer. These solutions account for the periodic nature of the cosine function.
Step 1: Identify the General Solution
The equation \(\cos \theta = \frac{1}{\sqrt{2}}\) has general solutions given by:
\[
\theta = \frac{\pi}{4} + 2\pi k \quad \text{and} \quad \theta = \frac{7\pi}{4} + 2\pi k
\]
where \(k\) is any integer.
Step 2: Determine Specific Solutions in the Interval \([0, 2\pi]\)
To find specific solutions within the interval \([0, 2\pi]\), we evaluate the general solutions for \(k = 0\):
Both values fall within the interval \([0, 2\pi]\).
Step 3: List the Specific Solutions
The specific solutions to the equation \(\cos \theta = \frac{1}{\sqrt{2}}\) in the interval \([0, 2\pi]\) are:
\[
\theta_1 = \frac{\pi}{4} \quad \text{and} \quad \theta_2 = \frac{7\pi}{4}
\]
Final Answer
The specific solutions are:
\[
\boxed{\frac{\pi}{4}, \frac{7\pi}{4}}
\]