[tex]sina=0.34 [/tex] has already been calculated for us, but to calculate the angle, which is what I'm assuming you want to know, we must take the inverse trigonometric function of sin.
From: [tex]sina=0.34[/tex], we can derive that:
[tex]a=sin ^{-1} 0.34[/tex]
Using a scientific calculator to solve this, we can see that the degrees that a is equal to (rounded to the nearest degree) is:
[tex]a=20[/tex]°
Wish you luck! :)