The side opposite x° and the hypotenuse are given. That means the relevant trig relation is ...
Sin = Opposite/Hypotenuse
sin(x°) = 6/11
The value of the angle is found using the inverse sine function:
x° = arcsin(6/11) ≈ 33.056°
x ≈ 33
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<em>Additional comment</em>
If you recall, the side length ratios of the "special" 30°-60°-90° triangle are 1:√3:2. Here, you have a shortest:longest side ratio that is 6:11 ≈ 6:12 = 1:2. This means the angle will be only slightly greater than 30°.
