In order to find the missing angle y we need to use a trigonometric function in this case the cosine because is the one that relates the adjacent side and the hypotenuse
[tex]\cos (\theta)=\frac{AS}{H}[/tex]
where
θ=y
AS=8
H=13
then we substitute the values
[tex]\cos (y)=\frac{8}{13}[/tex]
then we isolate the y
[tex]y=\cos ^{-1}(\frac{8}{13})[/tex][tex]y=52.02\text{\degree}[/tex]
