The answer is the first option, [tex] \frac{12}{13} .[/tex]
Start by knowing that the cosine function is [tex] \frac{adj}{hyp} [/tex].
For angle θ, find the adjacent side and hypothesis of the given triangle. These are 24 and 26, respectively. Simply put those into the cosine function, simplify, and you have your answer.
[tex]\cos(\theta)= \frac{adj}{hyp} = \frac{24}{26} = \frac{12}{13}[/tex]
