well, as we can see, the cos(x) as well as the sin(x) are both positive, that puts the angle in the I Quadrant only, everywhere else they differ in signs or are both negative.
that simply means it has an adjacent side of 3, opposite side of 4, and a hypotenuse of 5, like you see it in the picture below.
and we can get the inverse function of either function to get about 53.130102354° for ∡x.
