Lets draw a picture:
where a is the side opposide to 60 and b is the side opposide to 30.
Since we have a right triangle, we can apply a trigonometric function. For instance, if we apply sine function, we get
[tex]\sin 60=\frac{a}{20}[/tex]then, a is given by
[tex]a=20\cdot\sin 60[/tex]since sin60=0.866, then a is equal to
[tex]a=20(0.866)[/tex]therefore, the answer is a = 50.23.
