Answer:
[tex]\displaystyle x=\left\{\frac{\pi}{4}, \frac{5\pi}{4}\right\}[/tex]
Step-by-step explanation:
We want to solve the equation:
[tex]\cos(x)\tan(x)=\cos(x)[/tex]
On the interval [0, 2π).
First, we can subtract cos(x) from both sides:
[tex]\cos(x)\tan(x)-\cos(x)=0[/tex]
Factor:
[tex]\cos(x)\left(\tan(x)-1\right)=0[/tex]
Zero Product Property:
[tex]\cos(x)=0\text{ or } \tan(x)-1=0[/tex]
Solve for each case:
[tex]\cos(x)=0\text{ or }\tan(x)=1[/tex]
Using the unit circle:
[tex]\displaystyle x=\left\{\frac{\pi}{4}, \frac{\pi}{2}, \frac{5\pi}{4}, \frac{3\pi}{2}\right\}[/tex]
However, since tangent isn't defined for π/2 and 3π/2, we remove them from our solutions. Hence:
[tex]\displaystyle x=\left\{\frac{\pi}{4}, \frac{5\pi}{4}\right\}[/tex]
