Answer: option D
Step-by-step explanation:
Remember the cosine identity:
[tex]cos\alpha=\frac{adjacent}{hypotenuse}[/tex]
Given the right triangle DFE shown in the image, you can identify that the adjacent side and the hypotenuse for the angle F of this triangle are:
[tex]adjacent=15\\hypotenuse=25[/tex]
Now you can substitute values into [tex]cos\alpha=\frac{adjacent}{hypotenuse}[/tex] and then reduce the fraction.
THerefore you get:[tex]cos(F)=\frac{15}{25}\\\\cos(F)=\frac{3}{5}[/tex]
