Someone please help me, I don't know the answer

Answer:
[tex]\cos(\beta)=\frac{11}{12}[/tex]
Step-by-step explanation:
let AC = x.
According to the pythagorean theorem,
[tex]x^2 + (2\sqrt{23})^2 = 24^2\\x^2 + 92 = 576\\x^2 = 484\\x = 22[/tex]
The cosine function is defined as the relationship between an angle and the ratio between the side adjacent to that angle and the hypotenuse.
[tex]\cos(\beta)=\frac{\text{AC}}{\text{AB}}=\frac{22}{24}=\frac{11}{12}[/tex]