Respuesta :

Answer:

[tex]\frac{11}{13}[/tex]

Step-by-step explanation:

[tex]\boxed{cos(2\theta)=2cos\theta-1}[/tex]

[tex]cos(2\theta)=2(\frac{12}{13} )-1[/tex]

            [tex]=\frac{11}{13}[/tex]