Question 1149059
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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  {{{sqrt(2.2^2 + 4.6^2)}}} = {{{sqrt(26)}}}.



Third,  

    sin(a) = {{{1.1/sqrt(26)}}} = 0.216,     (1)

where "a" is the angle under the question.



Now use your calculator to find "a" from equation (1), your answer.
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Solved.