Here, we must use the cos(x) rule…
Cos(x)=A/H
Here, the adjacent side is 3 and the hypotenuse is 8.
Thus,
Cos(x)=3/8
To find x, take the cosine inverse of both sides
cos^-1(cos(x))= cos^-1(3/8)
Thus x=cos^-1(3/8)
Thus, x is approximately 68 degrees.
Hope this helps!