Let the unknown angle be x.
That is
sin x = 4/5
cos x = 3/5
By drawing a right triangle in the first quadrant,
hypotenuse = 5
Adjacent side = 3
opposite side = 4
That is tan x = 4/3
From the calculator,
x = arctan(4/3) = 53 deg (nearest integer)
Answer: 53 deg. (nearest integer)