.
First, the height of the ramp is half of its shorter edge, i.e. 2.2/2 = 1.1 m.
Second, the length of the diagonal of the ramp is   =
 =  .
Third,  
    sin(a) =
.
Third,  
    sin(a) =  = 0.216,     (1)
where "a" is the angle under the question.
Now use your calculator to find "a" from equation (1), your answer.
 = 0.216,     (1)
where "a" is the angle under the question.
Now use your calculator to find "a" from equation (1), your answer.
Solved.