Explanation:
first we need the length of the Hypotenuse (UW).
Pythagoras :
c² = a² + b²
with c being the Hypotenuse (the side opposite of the 90 degree angle).
UW² = 76² + 39² = 5,776 + 1,521 = 7,297
UW = sqrt(7297) = 85.42247948...
now we get x from the law of sine :
sinA/a = sinB/b = sinC/c
with the angles always being opposite of the sides.
so, we have
sin(x)/39 = sin(90)/sqrt(7297) = 1/sqrt(7297)
sin(x) = 39/sqrt(7297) = 0.456554296...
x = 27.16498506...° ≈ 27.2°
we could have done it without the Hypotenuse first.
as the angle W is 90-x
sin(x)/39 = sin(90-x)/76 = cos(x)/76
sin(x)/cos(x) = 39/76 = tan(x) = 0.513157895...
x = 27.16498506...° ≈ 27.2°
as expected, it is precisely the same result.