Using trigonometric identities, it is found that the value of [tex]\cos{\theta}[/tex] is given by:
B. [tex]\cos{\theta} = \frac{\sqrt{17}}{6}[/tex]
What is the tangent of an angle?
It is given by the division of it's sine by it's cosine, that is:
[tex]\tan{\theta} = \frac{\sin{\theta}}{\cos{\theta}}[/tex]
In this problem, the equation given is:
[tex]\tan{\theta} = -\sqrt{\frac{19}{17}}[/tex]
That is:
[tex]\frac{\sin{\theta}}{\cos{\theta}} = -\sqrt{\frac{19}{17}}[/tex]
[tex]\sin{\theta} = -\sqrt{\frac{19}{17}}\cos{\theta}[/tex]
The following identity is applied:
[tex]\sin^2{\theta} + \cos^2{\theta} = 1[/tex]
Then:
[tex]\left(-\sqrt{\frac{19}{17}}\cos{\theta}\right)^2 + \cos^2{\theta} = 1[/tex]
[tex]\frac{36}{17}\cos^2{\theta} = 1[/tex]
[tex]\cos^2{\theta} = \frac{17}{36}[/tex]
[tex]\cos{\theta} = \frac{\sqrt{17}}{6}[/tex]
More can be learned about trigonometric identities at https://brainly.com/question/24496175
