Since we have a right triangle, we can relate the given angle and the legs a and 20 by means of the tangent function ,that is,
[tex]\tan 30=\frac{20}{a}[/tex]
Since tangent of 30 degrees is
[tex]\text{tan}30=\frac{\text{ opposite side to angle 30}}{\text{ adjacent side to angle 30}}=\frac{1}{\sqrt[]{3}}[/tex]
we have that
[tex]\frac{1}{\sqrt[]{3}}=\frac{20}{a}[/tex]
Then, by cross multiplying the numbers, we have
[tex]1\times a=20\times\sqrt[]{3}[/tex]
Therefore, we have:
[tex]a=20\sqrt[]{3}=34.64[/tex]
By rounding to the nearest whole number, the answer is: 35 units
